This patch adds a `pdf-docs` tox target that will build
PDF versions of our docs. As per the Train community goal:
https://governance.openstack.org/tc/goals/selected/train/pdf-doc-generation.html
Add sphinxcontrib-svg2pdfconverter to doc/requirements.txt
to convert our SVGs.
Change-Id: I8b8d50dbf2329f8f972a0d9d734d788009dbc852
Story: 2006105
sphinxmark is no longer compatible with the latest release of Sphinx
which is causing all of our documentation jobs to fail. This patch
removes it as our current usage of openstacktheme for documentation
already provides watermarks for current branch and notices for which
branch the documentation covers.
Change-Id: I5867bf30dcfe13700e24dca528704dc21ae52b13