Release Notes for 2.5.2

Staged at:
http://stg-web101.sw.joyent.continuuity.net/cdap/2.5.2-r2.5.2_release_notes/en/reference-manual/release-notes.html
Maybe omit `and their documentation` unless documentation is outside of the examples.

If not omitting, then `Tested and updated the Standalone CDAP examples and their documentation` may sound better.