Update git submodules

* Update helpcontent2 from branch 'master'
  - Related: tdf#121134: Changing http to https where possible
    
    Change-Id: I983391c76f7c73ad0edeb85faacdc088a9d73df6
    Reviewed-on: https://gerrit.libreoffice.org/62995
    Tested-by: Jenkins
Reviewed-by: Olivier Hallot <olivier.hallot@libreoffice.org>
    

helpcontent2 @ 3a506373

-Subproject commit 0846f79c26b9feb6246d3075b4fc49d7b7cdc11f
+Subproject commit 3a506373636d8c224dab844b4248a338d7a2e696