docs: Main docs update (#1304)

* Remove template in favor of official samples

* Fixed a variable name copy pasta mistake

line 35 was _database.GetData() instead of DBService.GetData()

* Experimental theme change

* Change paragraph, code, heading fonts
* Widen viewport

* Update DocFX.Plugins.LastModified v1.2.3

* Exclude Discord.API in docs

* Add remarks for SocketReaction properties

* Add examples for BaseSocketClient.Events

* Add additional clarification for some methods

* Move IUser and IGuildChannel examples

* Clarify several guides samples with notes

- Reword TypeReader comment to avoid giving the idea that the sample itself is "obsolete"
- Remove CommandException logging comment regarding C#7.0 as the version is now the standard across VS2017 and up
- Remove suggestion about handling result in command handler since it is now advised to use CommandExecuted instead
+ Add additional comment to clarify ctor for DI setup

* Add/migrate code examples

* Incorporate material design theme

License @ https://github.com/ovasquez

* Update installation and nightly guide

* Fix improper indentations made obvious by the widen viewport
* Fix minor grammar issues
+ Add installation for nightly build using dotnet CLI

* Fix nav level indentation

* Revise "Your First Bot" article

* Merge some paragraphs to avoid clutter while keeping readability
* Reword the use of command framework
+ Add additional warning/note about environment variable

* Add additional indent level

* Fix indentation text warping

* Remove connections sample

* Update logging sample

Remove redundant part of the sample

* Remove mention of RPC

* Remove misleading section about commands

- Remove command sample from complete snippet
* Revise "Your First Bot" command paragraphs
* Change wording to hint devs that additional command parser packages may be available, as more and more begin to crop up

* Update themes

* Add XML docs contribution guidelines


Update guidelines

* Update CommandExecuted remarks

* Fix precondition remarks typo
no one saw that ok

* Fix permission sample in docfx

* Fix IMessageChannel samples

* Update docs/_template/light-dark-theme/styles/docfx.vendor.minify.css

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

* Update docs/_template/light-dark-theme/styles/material.css

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

* Update docs/_template/light-dark-theme/styles/material.css

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

docs/guides/commands/samples/dependency-injection/dependency_map_setup.cs

@@ -3,6 +3,9 @@ public class Initialize
 	private readonly CommandService _commands;
 	private readonly DiscordSocketClient _client;
 
+	// Ask if there are existing CommandService and DiscordSocketClient
+	// instance. If there are, we retrieve them and add them to the
+	// DI container; if not, we create our own.
 	public Initialize(CommandService commands = null, DiscordSocketClient client = null)
 	{
 		_commands = commands ?? new CommandService();

docs/guides/commands/samples/dependency-injection/dependency_module.cs

@@ -32,6 +32,6 @@ public class DatabaseModule : ModuleBase<SocketCommandContext>
     [Command("read")]
     public async Task ReadFromDbAsync()
     {
-        await ReplyAsync(_database.GetData());
+        await ReplyAsync(DbService.GetData());
     }
-}
+}

docs/guides/commands/samples/intro/command_handler.cs

@@ -3,6 +3,7 @@ public class CommandHandler
     private readonly DiscordSocketClient _client;
     private readonly CommandService _commands;
 
+    // Retrieve client and CommandService instance via ctor
     public CommandHandler(DiscordSocketClient client, CommandService commands)
     {
         _commands = commands;
@@ -46,19 +47,9 @@ public class CommandHandler
 
         // Execute the command with the command context we just
         // created, along with the service provider for precondition checks.
-        
-        // Keep in mind that result does not indicate a return value
-        // rather an object stating if the command executed successfully.
-        var result = await _commands.ExecuteAsync(
+        await _commands.ExecuteAsync(
             context: context, 
             argPos: argPos,
             services: null);
-
-        // Optionally, we may inform the user if the command fails
-        // to be executed; however, this may not always be desired,
-        // as it may clog up the request queue should a user spam a
-        // command.
-        // if (!result.IsSuccess)
-        // await context.Channel.SendMessageAsync(result.ErrorReason);
     }
 }

docs/guides/commands/samples/post-execution/command_exception_log.cs

@@ -1,6 +1,5 @@
 public async Task LogAsync(LogMessage logMessage)
 {
-    // This casting type requries C#7
     if (logMessage.Exception is CommandException cmdException)
     {
         // We can tell the user that something unexpected has happened

docs/guides/commands/samples/typereaders/typereader.cs

@@ -1,5 +1,6 @@
-// Note: This example is obsolete, a boolean type reader is bundled 
-// with Discord.Commands
+// Please note that the library already supports type reading
+// primitive types such as bool. This example is merely used
+// to demonstrate how one could write a simple TypeReader.
 using Discord;
 using Discord.Commands;