[docs] Add async with documentation for Client

Co-authored-by: Rapptz <[email protected]>

discord/client.py

@@ -136,6 +136,14 @@ class Client:
     r"""Represents a client connection that connects to Discord.
     This class is used to interact with the Discord WebSocket and API.
 
+    .. container:: operations
+
+        .. describe:: async with x
+
+            Asynchronously initialises the client and automatically cleans up.
+
+            .. versionadded:: 2.0
+
     A number of options can be passed to the :class:`Client`.
 
     Parameters

discord/ext/commands/bot.py

@@ -1220,6 +1220,14 @@ class Bot(BotBase, discord.Client):
     This class also subclasses :class:`.GroupMixin` to provide the functionality
     to manage commands.
 
+    .. container:: operations
+
+        .. describe:: async with x
+
+            Asynchronously initialises the bot and automatically cleans up.
+
+            .. versionadded:: 2.0
+
     Attributes
     -----------
     command_prefix
@@ -1277,3 +1285,5 @@ class Bot(BotBase, discord.Client):
 
         .. versionadded:: 1.7
     """
+
+    pass