[FAB-10590] Discovery CLI documentation
[FAB-10590] Discovery CLI documentation

This change set adds a markdown file which serves as documentation
for the discovery CLI tool.

Change-Id: I41cd081c27952a5f71142a31435a5787663ab3ce
Signed-off-by: yacovm <632344b5da9bd743456189af4db4b56472defb8c@il.ibm.com>

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