[Buildbot] #3313: Improve nine migration notes

[Buildbot trac]

#3313: Improve nine migration notes
------------------------+-------------------
Reporter:  dustin       |      Owner:
    Type:  enhancement  |     Status:  new
Priority:  major        |  Milestone:  0.9.0
 Version:  0.8.10       |   Keywords:
------------------------+-------------------
 From Vitali

 ----

 Some of migration notes are called out in release notes.  Many are
 missing.

     Release notes are long, talk about other things. Some notes are
 difficult to connect the dots to as the cause.
     A lot of times things are mentioned as removed with no-to minimal
 discussion about how to replace them.  The obvious one is how to migrate
 messageFormatter in MailNotifier.
     An explicit migration guide may be needed depending on other people’s
 experiences

--
Ticket URL: <http://trac.buildbot.net/ticket/3313>
Buildbot <http://buildbot.net/>
Buildbot: build/test automation