FAB-83: Expose status of Jenkins build in index.md

Add markdown view Jenkins build status url in index.md. This gives
flexiblity to the user to view Jenkins build status from documentation.

Change-Id: Ic661207d6fce01ebb60c5b4654458af22ccc54f0
Signed-off-by: rameshthoomu <rameshbabu.thoomu@gmail.com>

docs/index.md

@@ -5,6 +5,7 @@ community and documented [here](https://goo.gl/RYQZ5N). Information on what
 _Incubation_ entails can be found in the [Hyperledger Project Lifecycle
 document](https://goo.gl/4edNRc).
 
+[![Build Status](https://jenkins.hyperledger.org/buildStatus/icon?job=fabric-merge-x86_64)](https://jenkins.hyperledger.org/view/fabric/job/fabric-merge-x86_64/)
 [![Go Report Card](https://goreportcard.com/badge/github.com/hyperledger/fabric)](https://goreportcard.com/report/github.com/hyperledger/fabric)
 [![GoDoc](https://godoc.org/github.com/hyperledger/fabric?status.svg)](https://godoc.org/github.com/hyperledger/fabric)
 [![Documentation Status](https://readthedocs.org/projects/hyperledger-fabric/badge/?version=latest)](http://hyperledger-fabric.readthedocs.io/en/latest/?badge=latest)