IM instructions need to be updated

[RomanPro100]

Now that keyboard layouts have been reworked in Cinnamon 6.6 and IBus input methods are integrated better into the system, using fcitx is no longer necessary and setups for all languages can be done with IBus.

For all languages the algorithm seems to be just:

1. Install the corresponding ibus-* package(s) (and possibly fonts)
2. Open Input Method app and select the IBus input method framework
3. Relogin/reboot
4. In Keyboard > Layouts settings, add the corresponding layout
5. (if needed) Configure the layout with "Configure"