Update git submodules

* Update helpcontent2 from branch 'master'
  - Improve donation link in Help online
    
    redmine#2815
    
    Addressed responsiveness: for screen width < 960px the
    button goes to the bottom of the screen and the header is
    not fixed anymore.
    
    Artists are invited to improve button rendering.
    
    Button max width is 300px, the en-US text and the translated
    text should fit in 2 lines of 300px each. Text is centered.
    
    Change-Id: I51860be2ad998e85f247118e44b21af3e2efa060
    Reviewed-on: https://gerrit.libreoffice.org/68644
    Tested-by: Jenkins
Reviewed-by: Olivier Hallot <olivier.hallot@libreoffice.org>
    

helpcontent2 @ bd26e706

-Subproject commit 8e550a4a314857e55602979b124a0c8953e7e4c2
+Subproject commit bd26e706b30dccecdeba24ba8b697ddf2fc7a615