doc: attempt to get the ayni JS into all head tags

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
doc: fix missing bracket

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
Merge pull request #2399 from ceph/wip-8366

doc: adds a navigational menu for docs

Reviewed-by: John Wilkins <john.wilkins@inktank.com>