Documentation: udev rules requirement not sufficiently obvious

[andrewgdotcom]

The need to install udev rules on linux is far from obvious. Ideally, if no U2F device is found and the OS is linux, the user should be prompted with a helpful hint.

Failing that, it should be flagged in the extension's info (under about:addons). Or failing that, it should be mentioned on the extension homepage (https://addons.mozilla.org/en-US/firefox/addon/u2f-support-add-on/) which is directly linked from the info. Currently the shortest path to the required information is four clicks, and that's after going to about:addons, which many people don't even know about...

[timmc-bcov]

A suggested repo documentation improvement (worked for me on Debian 8 Linux with Firefox 52.5.0 x64):

As root, save the contents of https://github.com/Yubico/libu2f-host/blob/master/70-u2f.rules to /etc/udev/rules.d/70-u2f-patch.rules and run udevadm control --reload-rules.

A suggested Mozilla Add-Ons page improvement:

Please see https://github.com/prefiks/u2f4moz for operating system specific setup if using Linux.