Fix various reference issues in documentation

Co-Authored-By: Riley Shaw <30989490+ShineyDev@users.noreply.github.com>

docs/ext/commands/api.rst

@@ -42,7 +42,7 @@ Event Reference
 These events function similar to :ref:`the regular events <discord-api-events>`, except they
 are custom to the command extension module.
 
-.. function:: on_command_error(ctx, error)
+.. function:: discord.ext.commands.on_command_error(ctx, error)
 
     An error handler that is called when an error is raised
     inside a command either through user input error, check
@@ -55,7 +55,7 @@ are custom to the command extension module.
     :param error: The error that was raised.
     :type error: :class:`.CommandError` derived
 
-.. function:: on_command(ctx)
+.. function:: discord.ext.commands.on_command(ctx)
 
     An event that is called when a command is found and is about to be invoked.
 
@@ -65,7 +65,7 @@ are custom to the command extension module.
     :param ctx: The invocation context.
     :type ctx: :class:`.Context`
 
-.. function:: on_command_completion(ctx)
+.. function:: discord.ext.commands.on_command_completion(ctx)
 
     An event that is called when a command has completed its invocation.
 
@@ -374,6 +374,9 @@ Exceptions
 .. autoexception:: discord.ext.commands.BadUnionArgument
     :members:
 
+.. autoexception:: discord.ext.commands.BadLiteralArgument
+    :members:
+
 .. autoexception:: discord.ext.commands.PrivateMessageOnly
     :members:
 
@@ -533,6 +536,7 @@ Exception Hierarchy
                         - :exc:`~.commands.TooManyFlags`
                         - :exc:`~.commands.MissingRequiredFlag`
                 - :exc:`~.commands.BadUnionArgument`
+                - :exc:`~.commands.BadLiteralArgument`
                 - :exc:`~.commands.ArgumentParsingError`
                     - :exc:`~.commands.UnexpectedQuoteError`
                     - :exc:`~.commands.InvalidEndOfQuotedStringError`