Add storage_opt to 2.2 schema

Signed-off-by: Joffrey F <[email protected]>

compose/config/config_schema_v2.2.json

@@ -235,6 +235,7 @@
         "stdin_open": {"type": "boolean"},
         "stop_grace_period": {"type": "string", "format": "duration"},
         "stop_signal": {"type": "string"},
+        "storage_opt": {"type": "object"},
         "tmpfs": {"$ref": "#/definitions/string_or_list"},
         "tty": {"type": "boolean"},
         "ulimits": {