README file browser

Nwg-readme-browser was conceived as rtfm with a graphical user interface.

It searches the /usr/share/doc path for README.* files, and displays them

in WebKit2.WebView. It supports .md, .rst, .html and plain text. It does

not support .pdf format. Although the program was written with nwg-shell

for sway and Hyprland in mind, it may also be used standalone.