Initial migration of wiki content over to src/docs

There will be a follow-up CL to ensure docs are following chromium’s style guide, links are fixed, etc. The file auditing was becoming too much for a single change and per Nico’s suggestion, it seems to be better to do

+ Bulk import with initial prune.
+ Follow-up CLs to clean up the documentation.

So that each CL has its own purpose.


Review URL:

Cr-Commit-Position: refs/heads/master@{#345186}
95 files changed