Mojo docs cleanup and add C++ struct/enum/union

Removes the silly Mojo "logo" thing because it's
unnecessary and breaks the title parsing logic in
gitiles markdown viewer.

BUG=None
[email protected]

Change-Id: I78d2139d64b1e6477b3284434d5022ff45070e89
Reviewed-on: https://chromium-review.googlesource.com/487262
Commit-Queue: Ken Rockot <[email protected]>
Reviewed-by: Ken Rockot <[email protected]>
Cr-Commit-Position: refs/heads/master@{#467179}
9 files changed