Rnote Translation Information

• When regenerating rnote.pot, all entries that have @..@ need to be removed or made sure to not be translated. These are placeholders and will be replaced when building the project with meson.
• The changelog should not be translated, so those entries ( from app.metainfo.xml.in ) need to be removed as well.
• Certain chinese locales are not listed in the LINGUAS file. This is because they are only symlinks to zh_hans and because weblate is configured to ignore these translations, it will always remove them from LINGUAS. However in practice this is not an issue, because meson's rnote-gmo target still compiles them to .mo files, and for windows the installer script includes the translations based on enumerating the files present in the po directory, not based on the locale strings present in LINGUAS. We just need to make sure we keep it this way. (discussed in more detail in #838)