[FAB-8273] Fix Jira link in root README.md
[FAB-8273] Fix Jira link in root README.md

Points the first Jira link in the root README.md to the main
Fabric dashboard in Jira.

Change-Id: I25a9bd13224860c77e81a58c57e294bd1c2c1c61
Signed-off-by: Sheehan Anderson <0f8d23b29bbdd001b628215e16a9924c573b94b4@gmail.com>

xixuejia/fabric,manish-sethi/fabric-sidedb,manish-sethi/fabric-sidedb,binhn/fabric,muralisrini/fabric,stemlending/fabric,binhn/fabric,hyperledger/fabric,manish-sethi/fabric-sidedb,jimthematrix/fabric,manish-sethi/fabric-sidedb,binhn/fabric,stemlending/fabric,manish-sethi/fabric,manish-sethi/fabric-sidedb,xixuejia/fabric,stemlending/fabric,manish-sethi/fabric-sidedb,muralisrini/fabric,stemlending/fabric,jimthematrix/fabric,xixuejia/fabric,hyperledger/fabric,manish-sethi/fabric-sidedb,manish-sethi/fabric,muralisrini/fabric