Restore README.md

It seems to have been deleted accidentially.

README.md

+Documentation (incomplete at this time, contribute if you can!) may be found at
+http://gluon.readthedocs.org/
+
+If you're new to Gluon and ready to get your feet wet, have a look at the
+[Getting Started Guide](http://gluon.readthedocs.org/en/latest/user/getting_started.html).
+
+**Gluon IRC channel: `#gluon` in [hackint](http://hackint.org/)**
+
+## Issues & Feature requests
+
+Before opening an issue make sure to read check whether any existing issues
+(open or closed) match. If you're suggesting a new feature, drop by on IRC or
+our mailinglist to discuss it first.
+
+## Use a release!
+
+Please refrain from using the master branch for anything else but development purposes!
+Use the most recent release instead. You can list all relaseses by running `git branch -a`
+and switch to one by running `git checkout v2015.1 && make update`.
+
+If you're using the autoupdater, do not autoupdate nodes with anything but releases.
+If you upgrade using random master commits the nodes *will break* eventually.
+
+## Mailinglist
+
+To subscribe to the list, send a message to:
+
+    gluon-subscribe@luebeck.freifunk.net
+
+To remove your address from the list, just send a message to
+the address in the `List-Unsubscribe` header of any list
+message. If you haven't changed addresses since subscribing,
+you can also send a message to:
+
+    gluon-unsubscribe@luebeck.freifunk.net