Add 10.1.4 release notes (akka#2154)

release notes for 10.1.3 (akka#2077)

* release notes for 10.1.3

* slight docs improvement in HttpServerExampleDocTest

Add release 10.1.2 release notes (akka#2058)

releasing 10.1.1

release 10.0.13

release 10.0.12

Releasing 10.1.0

Released v10.1.0 for Scala 2.13.0-M3 (with preliminary fixes)

Merge pull request akka#1851 from jrudolph/jr/10.1.0-RC2-release-notes

10.1.0-RC2 Release Notes

Releasing v10.1.0-RC1