[commands] Add missing description parameter to docs

discord/ext/commands/parameters.py

@@ -194,7 +194,7 @@ def parameter(
     description: str = empty,
     displayed_default: str = empty,
 ) -> Any:
-    r"""parameter(\*, converter=..., default=..., displayed_default=...)
+    r"""parameter(\*, converter=..., default=..., description=..., displayed_default=...)
 
     A way to assign custom metadata for a :class:`Command`\'s parameter.