Adds link to generated epub.

Author: lanijw

docs/about.mdx

@@ -8,6 +8,10 @@ Are you looking to start playing games with the _H-Group_? Head on over to [the
 
 Have you found your way here from the Internet? That's fine too. Feel free to cherry-pick strategies for your own group, or even adopt the whole convention framework. We enjoy talking to other Hanabi players, so make sure to say hi in the Discord server as well. (Discord is a voice and text chat application that you can run in a browser.)
 
+## E-Book Format
+
+For those who'd prefer to read this guide on an e-reader or simply access it offline, you can download the [epub version](https://hanabi.github.io/assets/epub/hgroup-conventions.epub). Please note that the epub version is an automatically converted version of the documentation at [hanabi.github.io](https://hanabi.github.io) and may therefore contain some content intended for the web version (e.g. this page's [Hotkeys section](#hotkeys)).
+
 ## Other Quick Links
 
 - [The rules of the game](https://github.com/hanabi/hanabi.github.io/blob/main/misc/rules.md) (written)