How to manually add custom information to the on-hover documentation that vscode provides when hovering on something

Question

I would like to complete or add custom information to the documentation that VSCode provides when sometimes it doesn't offer as much info as I want.

For example in CSS I've got

box-shadow: 2px 4px 10px 4px rgba(100, 100, 100, 0.5);

and when I hover over box-shadow it shows me this

I'ld like to be able to add to the syntax for example to add things like what each parameter of box-shadow does so when I forget I just quickly hover it and remember and same for other stuff that are missing some documentation.