feat: Apple add docs for graphQL option

### Description

Add docs for the option [`enableGraphQLOperationTracking`](https://github.com/getsentry/sentry-cocoa/blob/ce038db2be84dfa4768cfc8ddbd8bde053092357/Sources/Swift/Options.swift#L188-L190). Find out what exact behaviour this feature enables and add public-facing docs for it.
