Update git submodules

* Update helpcontent2 from branch 'master'
  - Help files: http -> https
    
    + some more conservative changes
    
    Change-Id: I0c5099f12438158ab6f9e4ac504612e2e2bea009
    Reviewed-on: https://gerrit.libreoffice.org/63213
    Tested-by: Jenkins
Reviewed-by: Olivier Hallot <olivier.hallot@libreoffice.org>
    

helpcontent2 @ 06c18977

-Subproject commit 0f2aec06d05584f3dcddcb29f1c43a70afef081e
+Subproject commit 06c18977efb48ac01627c139a70ae70008319f62