Docs build on python3 has some extra demands, like that a global
toctree argument (e.g. ocata/*) always needs to list at least one
file. To satisfy that, the easiest solution was to remove the
"approved" and "implemented" folders. We were not using them anyhow.
Change-Id: I453e74932b95cc8f3e13e1fb74437f3da86f659f