docs: Documentation December Update (#1218)

* Fix broken link (#11)

* Fix typos and improve wording

* Add information for IGuildUser

+ Add GetPermission sample
+ Add ModifyAsync remarks

* Add information for IGuildChannel

+ Add ModifyAsync remarks
+ Add GetOverwritePermissionAsync examples

* Add warning for Direction.Around

* Fix indentations and references

* Move IRole.ModifyAsync sample

* Add information for IUser

+ Add example, remarks for Get(Default)AvatarUrl
+ Add example, remarks for GetOrCreateDMChannelAsync
+ Add missing remarks/summary/returns for other properties of the class

* Change verbs used in IVoiceState summary/remarks

* Add additional explanation for IGuildUser.RoleIds

* Change verbs used in IMessage summary/remarks

* Clarify IUserMessage Add/RemoveReactionAsync samples

* Fix command handler sample typo

* Add information for DiscordSocketConfig

+ Add remarks/example to the class
+ Add remarks to AlwaysDownloadUsers

* Fix documentation for SlowMode

* Add additional remarks for Guild/TextChannelProperties

* Update DocFx.Plugins.LastModified to v1.2.0
This should drastically improve docfx build time.

* Add missing dependencies

* Update DocFx.Plugins.LastModified to v1.2.1

Improve performance

* Update DocFx.Plugins.LastModified to v1.2.2

* Clarify deployment.md

+ Rewritten .NET Core deployment strategies for better clarification
    * Split deployment types into framework-dependent and self-contained
    * Clarify the benefits of using different types of publishing
    * Include a sample of how to execute dotnet application with the dotnet command in a TIP dialog for visibility

* Update post-execution article and samples

+ This change is to reflect changes made in https://github.com/RogueException/Discord.Net/pull/1164, where CommandInfo is now passed into the CommandExecuted event as an Optional<T>

* Update DocFX.Plugin.DescriptionGenerator to v1.1.1

* Adjust according to recent CommandExecuted changes

See:
+ f549da50e0
+ 6260749095

* Add further documentation for https://github.com/RogueException/Discord.Net/pull/1037

* Add partial documentation for the precondition helper class

* Include CHANGELOG.md in docs

* Revise post-execution docs
* Fix incorrect Optional<T> usage
* Indent some sample code and add a comment reminding the user that the post-execution basic sample code is not ideal.

* Streamline docs for Attachment
+ This commit also adds further explanation for why Embeds and Attachments are read-only collections

* Add further documentation for MessageActivity and MessageApplication

* Add caching-related docs to ISocketMessageChannel

* Add missing documentation inheritance for SyncPermissionsAsync

* Streamline documentation process

This is done by changing the documentation of the implementations required by interfaces to redirect to the interface method instead (e.g., SocketDMChannel#GetMessagesAsync refer to IMessageChannel.GetMessagesAsync within the remarks of the method).

* Cleanup 92bf8363ca

* Update src/Discord.Net.Core/Entities/Channels/Direction.cs

Co-Authored-By: Still34 <341464@gmail.com>

* Update src/Discord.Net.Core/Entities/Channels/Direction.cs

Co-Authored-By: Still34 <341464@gmail.com>

* Update src/Discord.Net.Core/Entities/Channels/GuildChannelProperties.cs

Co-Authored-By: Still34 <341464@gmail.com>

* Update src/Discord.Net.WebSocket/DiscordSocketConfig.cs

Co-Authored-By: Still34 <341464@gmail.com>

* Update according to PR suggestions

* Reword sentences of deployment article for clarification & remove mention of portability
* Fix typos/grammar errors within TextChannelProperties

* Add the logo SVG to the page navbar

* Implement changing logo image based on theme color using CSS background image

* Add a favicon

* use the purple logomark instead of white

* hack? set the title to navbar svg to read "Discord.Net Docs"

docs/faq/commands/general.md

@@ -119,24 +119,29 @@ The following are the known caveats with `RunMode.Async`,
 3. [ExecuteAsync] will immediately return [ExecuteResult] instead of
  other result types (this is particularly important for those who wish
  to utilize [RuntimeResult] in 2.0).
-4. Exceptions are swallowed.
+4. Exceptions are swallowed in the `ExecuteAsync` result.
 
 However, there are ways to remedy some of these.
 
 For #3, in Discord.Net 2.0, the library introduces a new event called
-[CommandExecuted], which is raised whenever the command is
-**successfully executed**. This event will be raised regardless of
-the `RunMode` type and will return the appropriate execution result.
+[CommandService.CommandExecuted], which is raised whenever the command is executed. 
+This event will be raised regardless of
+the `RunMode` type and will return the appropriate execution result
+and the associated @Discord.Commands.CommandInfo if applicable.
 
 For #4, exceptions are caught in [CommandService.Log] event under
-[LogMessage.Exception] as [CommandException].
+[LogMessage.Exception] as [CommandException] and in the 
+[CommandService.CommandExecuted] event under the [IResult] as 
+[ExecuteResult.Exception].
 
 [Task.Run]: https://docs.microsoft.com/en-us/dotnet/api/system.threading.tasks.task.run
 [async state machine]: https://www.red-gate.com/simple-talk/dotnet/net-tools/c-async-what-is-it-and-how-does-it-work/
 [ExecuteAsync]: xref:Discord.Commands.CommandService.ExecuteAsync*
 [ExecuteResult]: xref:Discord.Commands.ExecuteResult
 [RuntimeResult]: xref:Discord.Commands.RuntimeResult
-[CommandExecuted]: xref:Discord.Commands.CommandService.CommandExecuted
+[CommandService.CommandExecuted]: xref:Discord.Commands.CommandService.CommandExecuted
 [CommandService.Log]: xref:Discord.Commands.CommandService.Log
 [LogMessage.Exception]: xref:Discord.LogMessage.Exception*
-[CommandException]: xref:Discord.Commands.CommandException
+[ExecuteResult.Exception]: xref:Discord.Commands.ExecuteResult.Exception*
+[CommandException]: xref:Discord.Commands.CommandException
+[IResult]: xref:Discord.Commands.IResult