rename varaible.js -> variable.js

01_Day/01_day_starter/index.html

@@ -11,7 +11,7 @@
         <button onclick="alert('Welcome to 30DaysOfJavaScript!');">Click Me</button>
         <script src="./helloworld.js"></script>
         <script src="./introduction.js"></script>
-        <script src="./varaible.js"></script>
+        <script src="./variable.js"></script>
         <script src="./main.js"></script>
 
 </body>