Add Keypress screencasting section

[quazar-omega]

Description

Short description of the changes: Added a section to cover the screencasting of keys, i.e. show on screen the keypresses of any type, including modifier keys.

Opened as draft to first see if https://github.com/ammgws/wshowkeys actually works or not and if yes move it to the "Where is my" section (and also remove the others?)

Checklist

I have:

• [x] 🤳 made sure that what I am adding is an app for end users, not a developer tool / library (no "wl-clipboard-rs")
• [x] 🔗 checked that the link I am using refers to the root of the project (example, https://mpv.io) or GitHub repo if the first is not available
• [x] 🤓 checked BOTH the name and the casing of the project(s) I am adding ("GNOME Terminal" and not "gnome-terminal", "bemenu" and not "Bemenu", etc.)
• [x] 💣 checked that I am using spaces for indentation and that my levels are correct (no tabs!)
• [x] ✋ checked that my section has the correct casing ("My section", and not "My Section")
• [x] 📝 checked that the projects and / or the section are alphabetically sorted ("Clipboard manager" then "Color picker", "bemenu" then "Fuzzel")

[quazar-omega]

After trying several things as per #184, I ended up finding the key (sorry) with https://github.com/AlynxZhou/showmethekey.
It requires root access, but it's necessary for the way it scans the key presses, though another implementation based on portals could be technically possible and desirable. For now though, this works well enough.

I'll update the code as soon as I can