Add nord theme with license header, update all theme files with license

Dockerfile

@@ -2,6 +2,7 @@ FROM nginx:alpine
 COPY default.conf /etc/nginx/conf.d/default.conf
 COPY ash.css /usr/share/nginx/html/ash.css
 COPY gruvbox.css /usr/share/nginx/html/gruvbox.css
+COPY nord.css /usr/share/nginx/html/nord.css
 COPY config.js /usr/share/nginx/html/config.js
 COPY index.html /usr/share/nginx/html/index.html
 COPY noise.png /usr/share/nginx/html/noise.png