Add Build/Setup Instructions to Readme

Updated Readme file with Build and Setup instructions
for Projector and Indexer

Change-Id: Ia59ae732359f347c51498377c9b0098748d99d86
Reviewed-on: http://review.couchbase.org/38959
Reviewed-by: John Liang <johliang00@gmail.com>
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Reviewed-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>
Tested-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>