=doc Describe how to use microKernel with sbt-native-packager

(cherry picked from commit 6a79ad1287fb776eac1cac07a8a45dc0b597cede)

Conflicts:
	project/plugins.sbt
Merge pull request #16173 from akka/wip-native-packager-patriknw

=doc Describe how to use microKernel with sbt-native-packager