Document what OpenTelemetry defaults make sense to change for use with Sentry

### Description

Document what OpenTelemetry defaults make sense to change for use with Sentry, e.g.:
- ~~MongoDB queries do not have values but just `?` placeholders in the statement, there is a flag to change this in OpenTelemetry (https://opentelemetry.io/docs/zero-code/java/agent/instrumentation/#db-statement-sanitization)~~ we don't want to be recording query values
- HTTP headers are missing

Also add a note to warn about potential PII.