message: Make README more confident about the stability
diff: # Matrix Discord Bridge
  A bridge between [Matrix](http://matrix.org/) and [Discord](https://discordapp.com/).
  -Currently the bridge is alpha quality, but is usable.
  +Currently the bridge is in **Beta** and quite usable for everyday
  +bridging, with one or two bugs cropping up.
  ![Screenshot of Riot and Discord working together](screenshot.png)
  