Update config.schema.json (#324)

Removed the need to specify any menu titles. The code works with a
`Null` as-is. I'm not convinced the lack of a title saves screen space
as desired, but the code works without a title, there's no real reason
to specify one as its not essential, so perhaps we just relax the
schema?

There is one user requesting this. They can work with a schema warning
for now and this can be rolled into the next release, when there's more
changes.

config.schema.json

@@ -18,7 +18,6 @@
     }
   },
   "required": [
-    "title",
     "items"
   ],
   "additionalProperties": false,
@@ -231,7 +230,6 @@
       },
       "required": [
         "name",
-        "title",
         "type",
         "items"
       ],