This uses a special content script to update the README page to show the current keyboard shortcuts and, on Chrome, to allow them to be changed.
This is a very early attempt. I would like to do a proper help page, but it’s very difficult to do that in a way that doesn’t use .innerHTML but also allows the content scripts to run (they won’t run on bundled pages).
This is only early work, but not sure exactly how to proceed, so merging this now, and will work on other features whilst letting it percolate, and hopefully will come up with something closer to what I'd ideally like to implement.
In support of #165
* On Firefox it suggests a key for the newly-added command, but on Chrome it is not allowed, so it highlights that the command is not configured (needs much visual design work). * Switch "id" for "listen" to clean up the code a bit.