added forgeted function signature in uikit

uikit/uikit.d.ts

@@ -71,6 +71,13 @@ declare module UIkit {
          * @param  {function}      fn      A function to execute on confirmation
          */
         confirm(message:string, fn:() => any): void
+        /**
+         * Create a prompt dialog, where the user enter information
+         * @param  {string} message The message to display. Can be Html
+         * @param  {function} fn  A function to execute on confirmation. The function
+         * receive the new value as a parameter
+         */
+        prompt(message:string, fn:(newValue:string) => any): void
         /**
          * Create a prompt dialog, where the user enter information
          * @param  {string} message The message to display. Can be Html