doc: manifest: trivial typo and punctuation fixes

Change-Id: I5e21131fa1bb8804dd10dfc19413f309a73a8c56
Reviewed-on: http://gerrit.aldebaran.lan/30634
Reviewed-by: dmerejkowsky <dmerejkowsky@aldebaran-robotics.com>
Tested-by: gerrit
doc: fix and update manifest syntax

Change-Id: I75c2e0b040f53594bcc51e95e31fc3f4f2dfbbd6
Reviewed-on: http://gerrit.aldebaran.lan/30635
Reviewed-by: dmerejkowsky <dmerejkowsky@aldebaran-robotics.com>
Tested-by: gerrit