Updated README and added some shell utils

[cyruseuros]

I can split this into 2 PRs if you prefer it that way.

[esjeon]

Thanks for the PR. Here are my thoughts:

1. Maybe we can split the script into a new file or a gist, and provide its URL in README? I think the script is too big to be included.

2. This part is a bit confusing:

   draw borders on maximized windows. Sometimes windows are not in "monocle mode" as far as Krohkite is concerned, are maximized as far as KDE is concerned, and KDE does not draw borders on maximized windows by default.

   How about the one below?

   prevent borders from disappearing. When a window is marked "maximized" in Breeze theme, its borders are removed to save screen space. This behavior may not be preferable depending on your setup.