Adding Entity guides, flowcharts, better sample system. (#2054)

* initial

* Interaction glossary entry

* Sharded Interaction sample

* Renames into solution

* Debugging samples

* Modify target location for webhookclient

* Finalizing docs work, resolving docfx errors.

* Adding threaduser to user chart

* Add branch info to readme.

* Edits to user chart

* Resolve format for glossary entries

* Patch sln target

* Issue with file naming fixed

* Patch 1/x for builds

* Appending suggestions

docs/guides/entities/samples/casting.cs

@@ -0,0 +1,7 @@
+// Say we have an entity; for the simplicity of this example, it will appear from thin air.
+IChannel channel;
+
+// If we want this to be an ITextChannel so we can access the properties of a text channel inside of a guild, an approach would be:
+ITextChannel textChannel = channel as ITextChannel;
+
+await textChannel.DoSomethingICantWithIChannelAsync();

docs/guides/entities/samples/restentities.cs

@@ -0,0 +1,8 @@
+// RestUser entities expose the accent color and banner of a user.
+// This being one of the few use-cases for requesting a RestUser instead of depending on the Socket counterpart.
+public static EmbedBuilder WithUserColor(this EmbedBuilder builder, IUser user)
+{
+    var restUser = await _client.Rest.GetUserAsync(user.Id);
+    return builder.WithColor(restUser.AccentColor ?? Color.Blue);
+    // The accent color can still be null, so a check for this needs to be done to prevent an exception to be thrown.
+}

docs/guides/entities/samples/safety-cast-pass.cs

@@ -0,0 +1,10 @@
+private void MyFunction(IMessage message)
+{
+    // Here we do the reverse as in the previous examples, and let it continue the code below if it IS an IUserMessage
+    if (message is not IUserMessage userMessage)
+        return;
+
+    // Because we do the above check inline (don't give the statement a body),
+    // the code will still declare `userMessage` as available outside of the above statement.
+    Console.WriteLine(userMessage.Author);
+}

docs/guides/entities/samples/safety-cast-var.cs

@@ -0,0 +1,9 @@
+IUser user;
+
+// Here we can pre-define the actual declaration of said IGuildUser object,
+// so we don't need to cast additionally inside of the statement.
+if (user is IGuildUser guildUser)
+{
+    Console.WriteLine(guildUser.JoinedAt);
+}
+// Check failed.

docs/guides/entities/samples/safety-cast.cs

@@ -0,0 +1,8 @@
+IUser user;
+
+// Here we check if the user is an IGuildUser, if not, let it pass. This ensures its not null.
+if (user is IGuildUser)
+{
+    Console.WriteLine("This user is in a guild!");
+}
+// Check failed.

docs/guides/entities/samples/socketentities.cs

@@ -0,0 +1,11 @@
+public string GetChannelTopic(ulong id)
+{
+	var channel = client.GetChannel(81384956881809408) as SocketTextChannel;
+	return channel?.Topic;
+}
+
+public SocketGuildUser GetGuildOwner(SocketChannel channel)
+{
+	var guild = (channel as SocketGuildChannel)?.Guild;
+	return guild?.Owner;
+}

docs/guides/entities/samples/unboxing.cs

@@ -0,0 +1,9 @@
+IUser user;
+
+// Here we use inline unboxing to make a call to its member (if available) only once.
+
+// Note that if the entity we're trying to cast to is null, this will throw a NullReferenceException.
+Console.WriteLine(((IGuildUser)user).Nickname);
+
+// In case you are certain the entity IS said member, you can also use unboxing to declare variables.
+IGuildUser guildUser = (IGuildUser)user;