Update git submodules

* Update helpcontent2 from branch 'master'
  - Some optimizing bits in XSLT
    
    Change-Id: I27c29677cbf9c704d64b5ed49acc56b7a22432bd
    Reviewed-on: https://gerrit.libreoffice.org/68646
    Tested-by: Jenkins
Reviewed-by: Olivier Hallot <olivier.hallot@libreoffice.org>
    

helpcontent2 @ fd16b597

-Subproject commit bd26e706b30dccecdeba24ba8b697ddf2fc7a615
+Subproject commit fd16b597ba43092b77dd6c3dadbaddafa4e420ed