Users and admins should have a brief info on what's new in an available app release, and the possibility to have a direct link to a Changelog.

• in an additional changes.xml the app developer will be able to optionally specify "What's new" info consisting of up to 3 bullet points with up to 100 characters each. (Provided this can be read from the appstore with the new update info).
• in the changes.xml the app developer will be able to optionally specify a link to a changelog page.
• when an app update is available, below the "Update to x.y" button a "What's new?" text is shown. On click a popup is shown with that info (if given, a placeholder text otherwise), and a link to the changelog (if provided). If neither are provided, the "What's new?" label is not shown.
• the information is provided by the app store along the other meta information, in the user's language
• A "What's new" popover on corresponding app shows the same short info after update, until dismissed (like for the Server what's new).

Appeareance on the apps management:

Mockups by @jancborchardt