Add page on best practices

[allanday]

TingPing has written this useful page, which would be great to polish and add to the docs:

https://gist.github.com/TingPing/c2e2d4f3dfc536ccc0d930c4965f8573

One thing I wonder is how much of the advice is relevant beyond GTK - it would be good if the page could be more generic, and then have GTK-specific parts within it.

[TingPing]

For non-gtk users it basically comes down to "Use the Portals" and Gtk just happens to wrap those for you. The filesystem portion is fairly generic though.

[skierpage]

TingPing has written this useful page, which would be great to polish and add to the docs: https://gist.github.com/TingPing/c2e2d4f3dfc536ccc0d930c4965f8573

The gist is a 404 :slightly_frowning_face:

For non-gtk users it basically comes down to "Use the Portals"...

Flatpak docs now mention portals in "Basic concepts," "Desktop Integration," and elsewhere.

If there's nothing actionable here, maybe this can be closed.