Add Jenkins CI documentation

Review Request #1536 — Created Jan. 20, 2019 and updated — Latest diff uploaded

Review Board
This is a companion patch to the Jenkins CI integration patch. This adds
documentation on how to install and configure the Jenkins integration.

Testing Done:
Built manual and looked at the resulting HTML.

Reviewed at

Not sure what I'm supposed to put here or why it is called testing. Is this based upon pull requests? Because it kind of feels that way.