Update git submodules

* Update helpcontent2 from branch 'master'
  - Update links for missing Colibre icons
    
    Change-Id: I827b755259ac7dc8de9a706dc111fd021be22306
    Reviewed-on: https://gerrit.libreoffice.org/64783
    Tested-by: Jenkins
Reviewed-by: Olivier Hallot <olivier.hallot@libreoffice.org>
    

helpcontent2 @ 57a948eb

-Subproject commit fe0a1e4dbf6de65be1820553fba7b7e215013f85
+Subproject commit 57a948ebc79dc38ae8836e1599e5aefcd4995f0c