Update release notes
Update release notes

This hasn't been updated much this cycle since most of the changes were
internal and/or related to the build system.

Change-Id: Id8fe6954afda7ea8e8ea78d6914fc9d5fccfe908
Reviewed-on: http://review.couchbase.org/44292
Tested-by: Mark Nunberg <e7d42768707bf23038325b0b68d4b577e5f6064a@haskalah.org>
Reviewed-by: Sergey Avseyev <87f6d5e4fd3644c3c20800cde7fd3ad1569370b3@gmail.com>

senthilkumaranb/libcouchbase,mnunberg/libcouchbase,couchbase/libcouchbase,maxim-ky/libcouchbase,avsej/libcouchbase,kojiromike/libcouchbase,kojiromike/libcouchbase,signmotion/libcouchbase,mnunberg/libcouchbase,avsej/libcouchbase,couchbase/libcouchbase,mody/libcouchbase,senthilkumaranb/libcouchbase,signmotion/libcouchbase,maxim-ky/libcouchbase,senthilkumaranb/libcouchbase,maxim-ky/libcouchbase,avsej/libcouchbase,mody/libcouchbase,avsej/libcouchbase,PureSwift/libcouchbase,signmotion/libcouchbase,mody/libcouchbase,PureSwift/libcouchbase,kojiromike/libcouchbase,couchbase/libcouchbase,PureSwift/libcouchbase,couchbase/libcouchbase,avsej/libcouchbase,mnunberg/libcouchbase,mnunberg/libcouchbase,avsej/libcouchbase,couchbase/libcouchbase,PureSwift/libcouchbase,couchbase/libcouchbase,senthilkumaranb/libcouchbase,couchbase/libcouchbase,avsej/libcouchbase,kojiromike/libcouchbase,mnunberg/libcouchbase,mody/libcouchbase,signmotion/libcouchbase,maxim-ky/libcouchbase