* Add <releases> tag
* Update summary to match recommended style
https://freedesktop.org/software/appstream/docs/chap-Metadata.html#tag-summary
* Add copyright information
• value-missing : <!-- Copyright [year] [name] --> is not present
* Add update contact
• tag-missing : <update_contact> is not present
* release: Use quotes for filepaths
* release: Mention the need to update appdata file
* Use markdown format for changelog and release notes
* Changelog: remove indent for bullet points
* Changelog: use headings for releases
* Release_Notes: use headings
* Release_Notes: use bullet points
Co-authored-by: Peter F. Patel-Schneider <pfpschneider@gmail.com>