Update git submodules

* Update helpcontent2 from branch 'master'
  - Mute L10n for embedded specific string
    
    Change-Id: I208c5f5e8a7a65d19ce79055cd031f4c8d8921e8
    Reviewed-on: https://gerrit.libreoffice.org/57068
    Tested-by: Jenkins
Reviewed-by: Sophia Schröder <sophia.schroeder@libreoffice.org>
Reviewed-by: Adolfo Jayme Barrientos <fitojb@ubuntu.com>
    

helpcontent2 @ 3b921c76

-Subproject commit 2e878c0fb7d7ea39589c0b919d649ef109baf1d3
+Subproject commit 3b921c7604f80decfbba38bfe22ec1409ae244d7