Maintain Android app screenshots for app stores upstream

For automated adding of screenshots (and metadata) to app stores, several mechanisms exist such as metadata and Fastlane. This saves the maintainer a lot of manual work uploading screenshots to app stores when new screenshots are available. This is a widely used mechanism help release new versions of apps.

For the F-Droid app store, screenshots and metadata have been created to facilitate this. These can be found at https://gitlab.com/fdroid/fdroiddata/tree/master/metadata/org.videolan.vlc/en-US See featureGraphic.png and contents of phoneScreenshots.

The request is to move these screenshots upstream from the F-Droid repo to this repo. This will move screenshots to a more generic location allowing maintenance in one place for the benefit of all app stores.