Updated docs on UI profiling

[linear]

We need to update the docs on UI proflining for RN to indicate a few things:

1. the disclaimer should be in the docs like we have for Android: https://docs.sentry.io/platforms/android/profiling/
2. and a troubleshooting entry:
   https://docs.sentry.io/platforms/android/profiling/troubleshooting/#i-see-elevated-number-of-crashes-in-th[…]oid-runtime-when-profiling-is-activated

[linear]

RN-470