Documentation reorganization

The documentation now lives in documentation/ as a Sphinx
project. Older standalone documents which did not fit in entirely
or partially are kept in their original form in legacy/.

Change-Id: I978dcd6803730fccc27338f26e7a03cbc03d82c0
Add a new README and remove build.sh
Merge "Documentation reorganization" into develop
Merge "Add a new README and remove build.sh" into develop