This change creates a new page describing the usage of project tags
as well as adds in project tag information into existing projects
refs. The added document highlights the properties of a project
tag, the new API calls created, filtering/searching uses, and examples
for each.
This change also creates a release note for the changes made
that add project tags.
Change-Id: Icff11da9412378ae59c6f392f98b05475c7c501d
Partially-Implements: bp project-tags
0579dec0b9