Hints for texworks in main

Warnings

• asv-screenshot-no-media
  texworks.appdata.xml:236 -
  A screenshot must contain at least one image or video in order to be useful. Please add an <image/> to it.
• asv-tag-empty
  texworks.appdata.xml:247 - translation
  The mentioned tag is empty, which is highly likely not intended as it should have content.
• translations-not-found
  Unable to add languages information, even though a translation tag was present in the MetaInfo file. Please check that its value is set correctly, and all locale files are placed in the right directories (e.g. /usr/share/locale/*/LC_MESSAGES/ for Gettext .mo files).