Change the dependency with the testenv:docs
Change the dependency with the testenv:docs

Add the description for pep8, docs, pdf-docs, releasenotes, api-ref.
Change the pdf-docs and releasenotes's packages dependency with the
test docs requirement.

Story: 2008360

Change-Id: Ifcb28a340733b90329970be0078118d523b64bd3

openstack/nomad