Update git submodules

* Update helpcontent2 from branch 'master'
  - Related: tdf#121134: Changing http to https where possible
    
    Change-Id: Ib302c781800d05395be2bfb39a994dec192a3590
    Reviewed-on: https://gerrit.libreoffice.org/63021
    Tested-by: Jenkins
Reviewed-by: Olivier Hallot <olivier.hallot@libreoffice.org>
    

helpcontent2 @ 3a6e63bb

-Subproject commit 463c2be51dfd1c00dcc53d1047d8abe21109499f
+Subproject commit 3a6e63bbdfc95ab721f56d2486a5d1d9002e2c8c