[STAGING] - Update CMOS navigation from TOC discussion

From the CMOS TOC session, we came up with this updated navigation structure for the next iteration:

https://docs.google.com/document/d/1M5oROeWDYX02NaOLBM35zFWqzJox7R6evSsz-Ztlwzs/edit 

We should update this in staging, and add blank TODO pages.
These can be filled in at a later date.