Add extension comments

src/Discord.Net.Core/Extensions/DiscordClientExtensions.cs

@@ -1,24 +1,31 @@
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
 
 namespace Discord
 {
+    /// <summary> Extensions for <see cref="IDiscordClient"/>. </summary>
     public static class DiscordClientExtensions
     {
+        /// <summary> Gets the private channel with the provided ID. </summary>
         public static async Task<IPrivateChannel> GetPrivateChannelAsync(this IDiscordClient client, ulong id)
             => await client.GetChannelAsync(id).ConfigureAwait(false) as IPrivateChannel;
 
+        /// <summary> Gets the DM channel with the provided ID. </summary>
         public static async Task<IDMChannel> GetDMChannelAsync(this IDiscordClient client, ulong id)
             => await client.GetPrivateChannelAsync(id).ConfigureAwait(false) as IDMChannel;
+        /// <summary> Gets all available DM channels for the client. </summary>
         public static async Task<IEnumerable<IDMChannel>> GetDMChannelsAsync(this IDiscordClient client)
             => (await client.GetPrivateChannelsAsync().ConfigureAwait(false)).Select(x => x as IDMChannel).Where(x => x != null);
 
+        /// <summary> Gets the group channel with the provided ID. </summary>
         public static async Task<IGroupChannel> GetGroupChannelAsync(this IDiscordClient client, ulong id)
             => await client.GetPrivateChannelAsync(id).ConfigureAwait(false) as IGroupChannel;
+        /// <summary> Gets all available group channels for the client. </summary>
         public static async Task<IEnumerable<IGroupChannel>> GetGroupChannelsAsync(this IDiscordClient client)
             => (await client.GetPrivateChannelsAsync().ConfigureAwait(false)).Select(x => x as IGroupChannel).Where(x => x != null);
 
+        /// <summary> Gets the most optimal voice region for the client. </summary>
         public static async Task<IVoiceRegion> GetOptimalVoiceRegionAsync(this IDiscordClient discord)
         {
             var regions = await discord.GetVoiceRegionsAsync().ConfigureAwait(false);

src/Discord.Net.Core/Extensions/EmbedBuilderExtensions.cs

@@ -2,6 +2,7 @@ using System;
 
 namespace Discord
 {
+    /// <summary> Extensions for building an embed. </summary>
     public static class EmbedBuilderExtensions
     {
         /// <summary> Adds embed color based on the provided raw value. </summary>