Be consistent in how board docs are named and move all to index.rst.
This will make the URL to the board documentation predictable and easier
to remember.
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
Very brief documentation of the board as a placeholder, more info on
supported features will follow.
Signed-off-by: Anas Nashif <anas.nashif@intel.com>