fix(apple): IdleTimeout for iOS (#11581)

Explain that the idleTimeout only applies to user interaction
transactions.

Author: philipphofmann

docs/platforms/apple/common/configuration/options.mdx

@@ -187,7 +187,7 @@ Learn more about enriching events with the view hierarchy in our <PlatformLink t
 
 <ConfigKey name="idle-timeout" supported={["apple.ios"]}>
 
-The idle time, measured in ms, to wait until a transaction will be automatically finished. The transaction will use the end timestamp of the last finished span as the endtime for the transaction.
+The idle time, measured in ms, to wait until a <PlatformLink to="/tracing/instrumentation/automatic-instrumentation/#user-interaction-tracing">user interaction transaction</PlatformLink> will be automatically finished. The transaction will use the end timestamp of the last finished span as the endtime for the transaction.
 
 The default is `3000`.