* Update helpcontent2 from branch 'master'
  - Add info on convert-to filter names
    
    command line --convert-to option miss description of the internal
    names of the filters.
    
    The xhp file is generated by the python script based on the
    filter xcd's.
    
    P2:
    fix typo,
    Fix <filename>,
    Put modules in upercase.
    
    P3:
    reduce L10n workload with <embedvar>
    
    P4:
    Make xmllint happy again
    
    Change-Id: I455491b1f6a141688308d768b2822f051566ae53
    Reviewed-on: https://gerrit.libreoffice.org/70273
    Tested-by: Jenkins
Reviewed-by: Olivier Hallot <olivier.hallot@libreoffice.org>