Coroutines guide should warn about cancellation exceptions when transferring resources across suspension points

[dkhalanskyjb]

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Originally reported by Uli Luckas in the Kotlinlang Slack: https://kotlinlang.slack.com/archives/C1CFAFJSK/p1742815571506039?thread_ts=1742814326.569149&cid=C1CFAFJSK

The caveat with how withContext may drop closeable resources (https://github.com/Kotlin/kotlinx.coroutines/issues/3504) should be highlighted in the guide:

val socket = withContext(Dispatchers.IO) {
  Socket("localhost", 8080)
} // CancellationException can be thrown here, after the resource gets created
socket.use {
  // ...
}

The same goes for prompt cancellation guarantees in the other APIs.