The directory structure of the input web site now controls directory the layout of the
doc hierarchy. This simplifies authoring documents and enriches the UI we generate.
This also fixes the broken link problem with the GitHub staging sites. Most links work
now.
Our sitemap.xml now contains all that it should, and excludes stuff that it shouldn't contain.
* Generated docs for our protos.
Unfortunately this did require some manual touch-up, but nothing that'll
be impossible to automate I think. I still need to grab the mixer aspect
config protos, which is a bit harder because they live in the mixer
repo.
* Rename envoy-config to proxy-config, update document title and overview.