[Feature Request] Add documentation for editing static themes

**Is your feature request related to a problem? Please describe.**
Currently the ["Using Dev Tools"](..#using-dev-tools) section of the GitHub main page only tells contributors how to edit the Dynamic and Filter themes. What about Static? The config file is in the same directory and can be edited from the Dev Tools, but the syntax isn't explained...

**Describe the solution you'd like**
Add a couple sentences in the said section on the GitHub main page about the syntax for editing `static-themes.config`

**Additional context**
So contributors can also submit patches for the Static theme.