[V3 Core] Command group automatic help (#1790)

* decorator inheritence

* black format

* add autohelp

* modify commands to use autohelp

redbot/cogs/image/image.py

@@ -26,14 +26,13 @@ class Image:
     def __unload(self):
         self.session.close()
 
-    @commands.group(name="imgur")
+    @commands.group(name="imgur", autohelp=True)
     async def _imgur(self, ctx):
         """Retrieves pictures from imgur
 
         Make sure to set the client ID using
         [p]imgurcreds"""
-        if ctx.invoked_subcommand is None:
-            await ctx.send_help()
+        pass
 
     @_imgur.command(name="search")
     async def imgur_search(self, ctx, *, term: str):