With Feditext now accepting beta users, this adds it as the third
client to recommend so we have web and the dominant mobile platforms
covered.
This also removes the screenshots from the README, because it became a
mess trying to add a third one. Either the cells become very narrow, or
the table doubles in height. As the UI may also change over time, it
might be better to point folks at the apps instead who'll hopefully have
up to date screenshots in their storefronts.
This tries to revamp/restructure the installation guide. It's renamed to
"Getting Started" as it now contains a few more things than just the
installation, especially the deployment considerations which we didn't
use to spell out as much ahead of time.
Installation is now a section with the guides on their own. I've removed
a bit of redundancy like the user creation. I also removed the rogue
reverse proxy section in the Docker guide and lifted that into the
reverse proxy section.
