Add warning against direct cast & fix broken MD link

docs/faq/basic-operations.md

@@ -1,16 +1,18 @@
 # Basic Operations Questions
 
 ## How should I safely check a type?
+
+> [!WARNING]
+> Direct casting (e.g. `(Type)type`) is **the least recommended** 
+> way of casting, as it *can* throw an [InvalidCastException] 
+> when the object isn't the desired type.
+>
+> Please refer to [this post] for more details.
+
 In Discord.NET, the idea of polymorphism is used throughout. You may 
 need to cast the object as a certain type before you can perform any 
 action. 
 
-There are several ways to cast, with direct casting 
-`(Type)type` being **the least recommended**, as it *can* throw an 
-[InvalidCastException] when the object isn't the desired type. 
-
-Please refer to [this post] for more details.
-
 A good and safe casting example:
 
 [!code-csharp[Casting](samples/basics/cast.cs)]
@@ -83,6 +85,8 @@ reactions.
 Unfortunately, not at the moment. See [#401](https://github.com/RogueException/Discord.Net/issues/401).
    
 
+[IChannel]: xref:Discord.IChannel
+[ICategoryChannel]: xref:Discord.ICategoryChannel
 [IGuildChannel]: xref:Discord.IGuildChannel
 [ITextChannel]: xref:Discord.ITextChannel
 [IGuild]: xref:Discord.IGuild