Added note to release script to announce on ML
Fixed test bug, was using value that wasn't generated.
move to [1.0.0] SNAP
[DOCS] made it clearer that the _version is incremented by all write operations (deletes included)
[DOCS] updated json responses after #4310 and #4480

 - Removed "ok": true from response examples
 - Added "created" flag to index response examples
 - Replaced exists flag with found in delete response examples
[DOCS] Tidied up asciidoc for migration page