feat: 🏷️ Added title attribute in the interface Step

The `title` attribute was missing, and can be used without any errors.

Author: Adil

index.d.ts

@@ -15,6 +15,11 @@ declare module 'intro.js-react' {
      * Position of the tooltip.
      */
     position?: string;
+
+    /**
+     * The tooltip title.
+    */
+    title?:string
     /**
      * CSS class of the tooltip.
      */