apkeep: add page

[Managor]

• The page(s) are in the correct platform directories: common, linux, osx, windows, sunos, android, etc.
• The page(s) have at most 8 examples.
• The page description(s) have links to documentation or a homepage.
• The page(s) follow the content guidelines.
• The page(s) follow the style guide.
• The PR title conforms to the recommended templates.
• Version of the command being documented (if known):

[Managor]

This page is bit barebones. If anyone thinks they see any worthwhile commands in the documentation, please add them.

[sebastiaanspeck]

Maybe add l to list available versions for an APK and add the example how to download from a different store d?