dev-doc: fix to release process docs

Change-Id: I916e7ff1af211baef1c6d56fd44d292ee6983599
Signed-off-by: Freddie Chopin <freddie.chopin@gmail.com>
Reviewed-on: http://openocd.zylin.com/1368
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>