Where to change grails.resources.adhoc.patterns

Question

I am develping a website in Grails

the image location is at C:\website\web-app\img the css location is at C:\website\web-app\css

My CSS

.footer-stay-connected a {
  width: 115px;
  height: 40px;
  background: url(../img/stay-connected.png);
}

I run-app in local, the background image gets changed

.footer-stay-connected a {
    width: 115px;
    height: 40px;
    background: url(resource:/img/stay-connected.png);
}

This causes resource not found because now my browser is trying to find the image at

http://localhost/website/static/css/resource:/img/stay-connected.png

From this page, http://grails-plugins.github.io/grails-resources/guide/9.%20Configuration.html

grails.resources.adhoc.patterns = ["/images/*", "*.css", "*.js"]

I seems to me that this might be an issue with Resource plugin configuration. It works when i renamed my image folder from "img" to "images"

Where can I find grails.resources.adhoc.patternsso i can change from "images" to "img"