Update sphinx and fix documentation issues

discord/ext/commands/bot.py

@@ -548,7 +548,7 @@ class BotBase(GroupMixin):
             The cog does not inherit from :class:`.Cog`.
         CommandError
             An error happened during loading.
-        .ClientException
+        ClientException
             A cog with the same name is already loaded.
         """
 

discord/ext/commands/converter.py

@@ -130,9 +130,9 @@ class Converter(Protocol[T_co]):
 
         Raises
         -------
-        :exc:`.CommandError`
+        CommandError
             A generic exception occurred when converting the argument.
-        :exc:`.BadArgument`
+        BadArgument
             The converter failed to convert the argument.
         """
         raise NotImplementedError('Derived classes need to implement this.')

discord/ext/commands/core.py

@@ -1184,7 +1184,7 @@ class GroupMixin(Generic[CogT]):
 
         Raises
         -------
-        :exc:`.CommandRegistrationError`
+        CommandRegistrationError
             If the command or its alias is already registered by different command.
         TypeError
             If the command passed is not a subclass of :class:`.Command`.