colourco.de was added to design resources

resources/design.json

@@ -217,6 +217,12 @@
       "desc": "Create a color palette with this helpful tool of Adobe.",
       "url": "https://color.adobe.com/",
       "tags": ["color", "palette"]
+    },
+    {
+      "title": "Color palette: Colourcode",
+      "desc": "colourco.de is an online designer tool, which allows you to easily and intuitively combine colours.",
+      "url": "https://colourco.de",
+      "tags": ["color", "palette"]
     }
   ]
 }