Add useful path to documentation

[PanderMusubi]

Please describe the problem would like to solve Some users are not aware where to look for application icons.

Describe the solution you'd like Add to the documentation that many useful icons can be found at

/usr/share/icons/hicolor/

[PanderMusubi]

Useful websites for animated icons to add to documentation are:

• https://emojipedia.org/telegram
• https://emojipedia.org/animated-noto-color-emoji

Note that these offer animated webp, see also https://github.com/timothycrosley/streamdeck-ui/issues/372

[PanderMusubi]