* Update the index page's description.
* Add a section about the hash ring to architecture.
* Add some new modules to, and remove some old modules from,
the developer doc quick links, to make the list of quicklinks
shorter and more useful.
* Correct a few broken links in the developer docs.
Change-Id: Ifac1dc355631a2d77b7ccdea362fb83ffbe6a4db
017f99120b