chore: add runkit example

Author: joscha

package.json

@@ -64,5 +64,6 @@
       "json",
       "node"
     ]
-  }
+  },
+  "runkitExampleFilename": "runkitExample.js"
 }

runkitExample.js

@@ -0,0 +1,10 @@
+const detective = require('detective-postcss');
+
+// list of imported file names (ex: 'bla.css', 'foo.css', etc.)
+const content = `
+    .my_class {
+        background: url("myFile.png");
+    }`;
+
+// or to also detect any url() references to images, fonts, etc.
+const allDependencies = detective(content, { url: true });