Improve documentation for catsEffectReleaseTimeout

[michaltomanski]

The catsEffectReleaseTimeout is applicable to the Akka/Pekko coordinated shutdown task, which is added to a specific phase. The phase timeout is configured separately via config files of Akka/Pekko. The timeout of a single task should not be higher than the timeout of the related phase.

Plus some minor fixes.

[what-the-diff]

PR Summary

• Refactoring property names in configurations
  The property names akka.coordinated-shutdown.exit-jvm and pekko.coordinated-shutdown.exit-jvm were simplified to coordinated-shutdown.exit-jvm in both Akka and Pekko systems. This should make configurations easier to understand.

• Expanded and Updated Comments
  The comments in several parts of the code have been improved, resulting in better documentation. Specifically, the descriptors for catsEffectReleaseTimeout, akkaReleaseTimeout, sharding and askTimeout parameters have been clarified in AkkaCluster, ShardingCommandSender, and PekkoCluster, respectively. These improvements will make it easier to understand how these parameters are used and their role within the overall system.