Suggestion: Add `menu.border` color

[black-black-cat]

Thanks so much for this theme @sdras!

The menu border is not distinguished from the background color. Can you add menu.border color?

When I add menu.border in custom, I found the border-width is wider than I expected. Is this border-width acceptable?

[sdras]

iirc that's why I didn't set it. I felt it was too bold and distracting. I'm ok with the menu border as-is, but we could add in the readme how to configure it if it bothers you (like I did with the sidebar, etc). Open to a PR for the README.

[phiter]

Hey @sdras I also had this issue with the menu not having a border, I think a very subtle border would look nice. Look at this:

I'm using

"workbench.colorCustomizations": {
    "[Night Owl (No Italics)]": {
        "menu.border": "#00000088"
    }
}