Documentation for saving files in html5.

**Your Godot version:**
3.6 beta 5
**Issue description:**
As far as I know, there is no documentation that shows how to save a data file (save game) in an html5 game, for example hosted on itch.io or other.
From what I know, I think it is done with javascript, you must access the indexDB and handle this to save a data file and retrieve it.
There is no documentation on how this should be done, there is no example project or anything like that.
My suggestion is a page to document this with example codes, of course.
**URL to the documentation page (if already existing):**