Add README section describing the licensing situation

README.md

@@ -6,7 +6,6 @@ This project started as a fork of Nick Denry's [Chimeverse](https://github.com/c
 
 ![Version](https://img.shields.io/npm/v/chimeverse/latest.svg)
 ![Downloads](https://img.shields.io/npm/dt/chimeverse.svg)
-![License](https://img.shields.io/npm/l/chimeverse.svg)
 <a href="https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=6MZ5YRYEDSVSQ&source=url" title="Donate once-off to this project using Paypal">
         <img src="https://img.shields.io/badge/paypal-donate-yellow.svg" alt="PayPayl donate button" />
     </a>
@@ -27,6 +26,24 @@ It should happen once. A very basic integration of [Converse.js](https://convers
 - Tray notifications
 - All the best from Converse.js like system notifications, MAM, OMEMO etc. See details at [Converse.js](https://conversejs.org/)
 
+
+#### License
+
+Like Converse.js, Converse-Desktop's files are released under the Mozilla
+Public License version 2 (MPLv2).
+
+The gist of this license is that the covered files must stay open source, and
+modifications to them need to be released under the same license, but new files
+(for example for your own plugin) don't have to be released under the same
+license.
+
+However, libsignal, which is required for OMEMO support is released under the
+GPLv3. The MPLv2 is compatible with GPLv3 and when GPLv3 code is included, the
+entire project effectively is licensed under the GPLv3.
+
+Any custom build of Converse-Desktop which removes libsignal will again be licensed under the MPLv2.
+
+
 #### Changelog
 
 See [CHANGES.md](https://github.com/conversejs/converse-desktop/blob/master/CHANGES.md)