Installation path

[styts]

When installing the tool outside of the predefined directory, the list command won't find the colorschemes.

One can either add to the README that DYNAMIC_COLORS_ROOT needs to be defined:

export DYNAMIC_COLORS_ROOT="$HOME/.urxvt/ext/dynamic-colors/"

...or dynamically determine the root from the script.

(Sorry, no PR - a bit in a hurry.)