Sphix 1.5 (I9e7261c4124b71eeb6bddd9e21747b61bbdc16fa) includes
"warning-is-error" which supersedes pbr's warnerrors. Enable this and
fix up the resulting failures
- trailing lines for lists in element_deps directive
- missing README's that are linked
- syntax error and highlighting in building instructions
Change-Id: I6549551b4a9bf47076c9811a7a38a666cbea2a50
