Add Wiki Documentation

[console-cowboy]

All facets of using the application should be implemented either in the README, or using the repository wiki. This includes any shortcuts, functionality, and instructions on enabling or disabling either.

[ghost]

Applications can just have help files built in. Besides this is not exactly the most complicated application that requires reading the docs before you can use it.

[fiaxh]

People shouldn't have to read a wiki/README in order to be able to use dino. If that's necessary we did something wrong. However there does exists a wiki page about supported XEPs. Shortcuts can be shown directly in the program using a GtkShortcutsWindow.

[NicoHood]

Does dino has shortcuts? I cannot find such a shortcut window.

[fiaxh]

@NicoHood Dino doesn't have shortcuts yet. I stated that solution because the issue explicitly mentioned shortcuts.