Help on how-to add autotext

Change-Id: Ia41a3478f5a59b4c13f676eb0e21d3b573456c8f
Reviewed-on: https://gerrit.libreoffice.org/10889
Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>