Add a paragraph to the Contributing Cloud Test Resources document's
Benefits to Contributors section about provider name visibility in
job logs, clarify that the significance of contribution necessary to
be listed on the Foundation site is at the discretion of the Infra
team, and use a more specific URL to a more specific anchor for that
list.
Change-Id: I41d46ece9a1547647a16023ab28b3cb4b2fa8419