fix broken link in heat cli-guide

In the current heat_client quickstart guide there is a link to the wordpress
templates that gets a 404 error. I have updated section_cli_heat.xml to reflect
https://github.com/openstack/heat-templates which is referenced as the proper
url in the bug description.

Change-Id: Ic23b6c4b11c35148ea3d386d3d6c22322eaefbcc
Fixes: bug #1203814
Merge "fix broken link in heat cli-guide"