=doc #3531 Recommend orElse’ing super.supervisorStrategy.decider
(cherry picked from commit 0d859f1424d6d874da49d5f0b501a53526ac524d)
Merge pull request #1663 from akka/wip-3531-orElse-decider-2.2-patriknw

=doc #3531 Recommend orElse’ing super.supervisorStrategy.decider (backport)