[docs] Add metadata and screenshots to the repository

[moeenio]

Speaking of contributions, we should make [the application] screenshots and metadata part of this repository, following the format used by the fastlane supply tool (which we could use as well), so they can be picked up by F-Droid and potentially automatically uploaded to Google Play via that fastlane thing, as well as to make it possible to collaboratively work on them and accept contributions.

Originally posted by @locness3 in #63 (comment)

• Screenshots
• Metadata

[micahlt]

Screenshots are already here, as well as a source file in the .afdesign format: https://github.com/Scratch-Client-4/itchy-ionic/tree/master/resources/screenshots

[moeenio]

Oh, thanks for providing a source file. It would be helpful to have it in an open format though.

[micahlt]

I agree - when I get around to it, I might be able to provide an SVG. However, at the moment it uses program-specific features that can't be converted to SVG without rasterization.