add a release guide

Even though there are very few steps involved, it is good to have it documented.

AUTHORS.md

@@ -2,9 +2,7 @@
 Below is a list of the contributors to Adaptive:
 
 + [Anton Akhmerov](<https://antonakhmerov.org>)
-+ [Bas Nijholt](<http://nijho.lt>)
 + [Christoph Groth](<http://inac.cea.fr/Pisp/christoph.groth/>)
-+ Jorn Hoofwijk
 + [Joseph Weston](<https://joseph.weston.cloud>)
 
 For a full list of contributors run