Cleanup FAQ section

+ Add introductory paragraphs to each FAQ section.
+ Add 'missing dependency' entry to commands FAQ.
* Split commands FAQ to 'General' and 'DI' sections.

docs/faq/basics/basic-operations.md

@@ -5,6 +5,10 @@ title: Questions about Basic Operations
 
 # Basic Operations Questions
 
+In the following section, you will find commonly asked questions and
+answers regarding basic usage of the library, as well as
+language-specific tips when using this library.
+
 ## How should I safely check a type?
 
 > [!WARNING]

docs/faq/basics/client-basics.md

@@ -5,6 +5,10 @@ title: Basic Questions about Client
 
 # Client Basics Questions
 
+In the following section, you will find commonly asked questions and
+answers about common issues that you may face when utilizing the
+various clients offered by the library.
+
 ## My client keeps returning 401 upon logging in!
 
 > [!WARNING]

docs/faq/basics/getting-started.md

@@ -5,6 +5,10 @@ title: Beginner Questions / How to Get Started
 
 # Basic Concepts / Getting Started
 
+In this following section, you will find commonly asked questions and
+answers about how to get started with Discord.Net, as well as basic
+introduction to the Discord API ecosystem.
+
 ## How do I add my bot to my server/guild?
 
 You can do so by using the [permission calculator] provided

docs/faq/commands/dependency-injection.md

@@ -0,0 +1,54 @@
+---
+uid: FAQ.Commands.DI
+title: Questions about Dependency Injection with Commands
+---
+
+# Dependency-injection-related Questions
+
+In the following section, you will find common questions and answers
+to utilizing dependency injection with @Discord.Commands, as well as
+common troubleshooting steps regarding DI.
+
+## What is a service? Why does my module not hold any data after execution?
+
+In Discord.Net, modules are created similarly to ASP.NET, meaning
+that they have a transient nature; modules are spawned whenever a
+request is received, and are killed from memory when the execution
+finishes. In other words, you cannot store persistent
+data inside a module. Consider using a service if you wish to
+workaround this.
+
+Service is often used to hold data externally so that they persist
+throughout execution. Think of it like a chest that holds
+whatever you throw at it that won't be affected by anything unless
+you want it to. Note that you should also learn Microsoft's
+implementation of [Dependency Injection] \([video]) before proceeding,
+as well as how it works in [Discord.Net](xref:Guides.Commands.DI#usage-in-modules).
+
+A brief example of service and dependency injection can be seen below.
+
+[!code-csharp[DI](samples/DI.cs)]
+
+[Dependency Injection]: https://docs.microsoft.com/en-us/aspnet/core/fundamentals/dependency-injection
+[video]: https://www.youtube.com/watch?v=QtDTfn8YxXg
+
+## Why is my `CommandService` complaining about a missing dependency?
+
+If you encounter an error similar to `Failed to create MyModule,
+dependency MyExternalDependency was not found.`, you may have
+forgotten to add the external dependency to the dependency container.
+
+Starting from Discord.Net 2.0, all dependencies required by each
+module must be present when the module is loaded into the
+[CommandService]. This means when loading the module, you must pass a
+valid [IServiceProvider] with the dependency loaded before the module
+can be successfully registered.
+
+For example, if your module, `MyModule`, requests a `DatabaseService`
+in its constructor, the `DatabaseService` must be present in the
+[IServiceProvider] when registering `MyModule`.
+
+[!code-csharp[Missing Dependencies](samples/missing-dep.cs)]
+
+[IServiceProvider]: xref:System.IServiceProvider
+[CommandService]: xref:Discord.Commands.CommandService

docs/faq/commands/commands.md → docs/faq/commands/general.md

@@ -1,10 +1,13 @@
 ---
-uid: FAQ.Commands
-title: Questions about Commands
+uid: FAQ.Commands.General
+title: General Questions about Commands
 ---
 
 # Command-related Questions
 
+In the following section, you will find commonly asked questions and
+answered regarding general command usage when using @Discord.Commands.
+
 ## How can I restrict some of my commands so only specific users can execute them?
 
 Based on how you want to implement the restrictions, you can use the
@@ -42,29 +45,6 @@ the last parameter.
 
 [RemainderAttribute]: xref:Discord.Commands.RemainderAttribute
 
-## What is a service? Why does my module not hold any data after execution?
-
-In Discord.Net, modules are created similarly to ASP.NET, meaning
-that they have a transient nature; modules are spawned whenever a
-request is received, and are killed from memory when the execution
-finishes. In other words, you cannot store persistent
-data inside a module. Consider using a service if you wish to
-workaround this.
-
-Service is often used to hold data externally so that they persist
-throughout execution. Think of it like a chest that holds
-whatever you throw at it that won't be affected by anything unless
-you want it to. Note that you should also learn Microsoft's
-implementation of [Dependency Injection] \([video]) before proceeding,
-as well as how it works in [Discord.Net](xref:Guides.Commands.DI#usage-in-modules).
-
-A brief example of service and dependency injection can be seen below.
-
-[!code-csharp[DI](samples/DI.cs)]
-
-[Dependency Injection]: https://docs.microsoft.com/en-us/aspnet/core/fundamentals/dependency-injection
-[video]: https://www.youtube.com/watch?v=QtDTfn8YxXg
-
 ## Discord.Net keeps saying that a `MessageReceived` handler is blocking the gateway, what should I do?
 
 By default, the library warns the user about any long-running event

docs/faq/commands/samples/missing-dep.cs

@@ -0,0 +1,29 @@
+public class MyModule : ModuleBase<SocketCommandContext>
+{
+    private readonly DatabaseService _dbService;
+    public MyModule(DatabaseService dbService)
+        => _dbService = dbService;
+}
+public class CommandHandler
+{
+    private readonly CommandService _commands;
+    private readonly IServiceProvider _services;
+    public CommandHandler(DiscordSocketClient client)
+    {
+        _services = new ServiceCollection()
+            .AddService<CommandService>()
+            .AddService(client)
+            // We are missing DatabaseService!
+            .BuildServiceProvider();
+    }
+    public async Task RegisterCommandsAsync()
+    {
+        // ...
+        // The method fails here because DatabaseService is a required
+        // dependency and cannot be resolved by the dependency
+        // injection service at runtime since the service is not
+        // registered in this instance of _services.
+        await _commands.AddModulesAsync(Assembly.GetEntryAssembly(), _services);
+        // ...
+    }
+}

docs/faq/misc/glossary.md

@@ -5,6 +5,12 @@ title: Common Terminologies / Glossary
 
 # Glossary
 
+This is an additional chapter for quick references to various common
+types that you may see within Discord.Net. To see more information
+regarding each type of object, click on the object to navigate
+to our API documentation page where you might find more explanation
+about it.
+
 ## Common Types
 
 * A **Guild** ([IGuild]) is an isolated collection of users and

docs/faq/misc/legacy.md

@@ -5,7 +5,10 @@ title: Questions about Legacy Versions
 
 # Legacy Questions
 
-## X, Y, Z does not work! It doesn't return a valid value anymore
+This section refers to legacy library-related questions that do not
+apply to the latest or recent version of the Discord.Net library.
+
+## X, Y, Z does not work! It doesn't return a valid value anymore.
 
 If you are currently using an older version of the stable branch,
 please upgrade to the latest pre-release version to ensure maximum

docs/faq/toc.yml

@@ -6,8 +6,12 @@
       topicUid: FAQ.Basics.BasicOp
     - name: Client Basics
       topicUid: FAQ.Basics.ClientBasics
-- name: Command
-  topicUid: FAQ.Commands
+- name: Commands
+  items: 
+    - name: General
+      topicUid: FAQ.Commands.General
+    - name: Dependency Injection
+      topicUid: FAQ.Commands.DI
 - name: Glossary
   topicUid: FAQ.Glossary
 - name: Legacy or Upgrade

docs/guides/commands/post-execution.md

@@ -31,7 +31,7 @@ be a violation of the SRP (Single Responsibility Principle).
 Another major issue is if your command is marked with
 `RunMode.Async`, [ExecuteAsync] will **always** return a successful
 [ExecuteResult] instead of the actual result. You can learn more
-about the impact in the [FAQ](xref:FAQ.Commands).
+about the impact in the [FAQ](xref:FAQ.Commands.General).
 
 ## CommandExecuted Event
 

src/Discord.Net.Commands/CommandService.cs

@@ -157,7 +157,7 @@ namespace Discord.Commands
         }
 
         /// <summary>
-        ///     Add a command module from a <see cref="Type" /> .
+        ///     Add a command module from a <see cref="Type" />.
         /// </summary>
         /// <example>
         ///     <para>The following example registers the module <c>MyModule</c> to <c>commandService</c>.</para>