Rename training-guide as training-guides

update jenkins-job-builder files layout.yaml projects.yaml. updates proper
name of project training-guides from former training-guide. updated
layout.yaml jobs and openstack/openstack-manuals sections. updated
projects.yaml manuals project section.

Change-Id: I37e1e0b9e3306d0bae34ee4b4982aaeb2686d3b5
Merge "Rename training-guide as training-guides"