Update README with image and basic install instructions

There may be errors, not tested for linux or osx

README.md

@@ -1,2 +1,26 @@
+![Gruvbox theme](https://raw.githubusercontent.com/alexanderbrevig/kicad-gruvbox-theme/main/kicad-gruvbox-theme.png) 
+
 # kicad-gruvbox-theme
 Gruvbox for KiCAD - THE FUTURE IS HERE
+
+
+Based on the original [Gruvbox](https://github.com/morhetz/gruvbox). 
+
+This is my KiCAD daily-driver theme.
+
+
+## Install theme
+
+- Linux `~/.config/kicad/colors` or `~/.config/kicad/6.0/colors`
+- Windows: `%APPDATA%\kicad\6.0\colors`
+- OSX: `~/Library/Preferences/kicad/colors` or `~/Library/Preferences/kicad/6.0/colors`
+
+You can simply `cd` your way there and get `Gruvbox.json` in there somehow. 
+
+    cd ~/.config/kicad/6.0/colors
+    curl https://raw.githubusercontent.com/alexanderbrevig/kicad-gruvbox-theme/main/Gruvbox.json > Gruvbox.json
+
+## Contribute
+
+I have not really landed on any convention as for when to use which color.
+Feel free to make suggestions or PR, I will probably merge them if you explain the thought behind your change.