Fixes rollup config docs

Author: Brad Janke

rollup.config.js

@@ -29,7 +29,7 @@ export default {
 		// npm, you'll most likely need these plugins. In
 		// some cases you'll need additional configuration —
 		// consult the documentation for details:
-		// https://github.com/rollup/rollup-plugin-commonjs
+		// https://github.com/rollup/plugins/tree/master/packages/commonjs
 		resolve({
 			browser: true,
 			dedupe: importee => importee === 'svelte' || importee.startsWith('svelte/')
@@ -68,4 +68,4 @@ function serve() {
 			}
 		}
 	};
-}
+}