Bootstrap sequence writeup and diagram

Added few more details as per John's comment

Change-Id: Ife062092ee1324b537aa2dd7df9b4a4aeb44a6ff
Reviewed-on: http://review.couchbase.org/34727
Reviewed-by: John Liang <john.liang@couchbase.com>
Reviewed-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>
Tested-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>