Change name back to arg

docs/rtk-query/api/fetchBaseQuery.mdx

@@ -105,7 +105,7 @@ Typically a string like `https://api.your-really-great-app.com/v1/`. If you don'
 
 _(optional)_
 
-Allows you to inject headers on every request. You can specify headers at the endpoint level, but you'll typically want to set common headers like `authorization` here. As a convenience mechanism, the second argument allows you to use `getState` to access your redux store in the event you store information you'll need there such as an auth token. Additionally, it provides access to `args`, `extra`, `endpoint`, `type`, and `forced` to unlock more granular conditional behaviors.
+Allows you to inject headers on every request. You can specify headers at the endpoint level, but you'll typically want to set common headers like `authorization` here. As a convenience mechanism, the second argument allows you to use `getState` to access your redux store in the event you store information you'll need there such as an auth token. Additionally, it provides access to `arg`, `extra`, `endpoint`, `type`, and `forced` to unlock more granular conditional behaviors.
 
 You can mutate the `headers` argument directly, and returning it is optional.