Update README for Arch Installs (#146)

Provided some simple information about gnome-keyring.

Changed the AUR link from `github-desktop` to `github-desktop-bin` to save user hassle.

README.md

@@ -48,7 +48,9 @@ $ snap install github-desktop --beta --classic
 ## Other Distributions
 
 Arch Linux users can install GitHub Desktop from the
-[AUR](https://aur.archlinux.org/packages/github-desktop/).
+[AUR](https://aur.archlinux.org/packages/github-desktop-bin/).
+
+`gnome-keyring` is required and the daemon must be launched either at login or when the X server is started. Normally this is handled by a display manager, but in other cases following the instructions found on the [Arch Wiki](https://wiki.archlinux.org/index.php/GNOME/Keyring#Using_the_keyring_outside_GNOME) will fix the issue of not being able to save login credentials.
 
 ## More information