Adding new files to helpcontent2/source/media/

Since <https://cgit.freedesktop.org/libreoffice/help/commit/?id=33551e7fd85aa327f76bb343a3740bceb162bbfa> "Properly handle language-specific parts of --with-help=html media/ sub-tree", whenever you add new files to helpcontent2/source/media/, please note that:

"All files in $(SRCDIR)/helpcontent2/source/media/ must now explicitly be listed in either helpcontent2/Package_html_media.mk (for the language-independent files) or helpcontent2/AllLangPackage_html_media_lang.mk (for the language-specific files). Also note the two TODOs in helpcontent2/AllLangPackage_html_media_lang.mk."

Thanks Stephan for the stride in the packaging of the new Help.

Kind regards