[WASM] Changed the demo to fibonacci calculation

wasm/app/index.html

@@ -29,10 +29,18 @@
     <h1>RustPython Demo</h1>
     <p>RustPython is a Python interpreter writter in Rust. This demo is compiled from Rust to WebAssembly so it runs in the browser</p>
     <p>Please input your python code below and click <kbd>Run</kbd>:</p>
-    <textarea id="code">x = 1
-y = 2
-print('Hello! x + y equals to ' + str(x+y))
-    </textarea>
+    <textarea id="code">n1 = 0
+n2 = 1
+count = 0
+until = 10
+
+print("These are the first " + str(until) + " number in a Fibonacci sequence:")
+
+while count < until:
+    print(n1)
+    n1, n2 = n2, n1 + n2
+    count += 1
+</textarea>
     <button id="run-btn">Run &#9655;</button>
     <script src="./bootstrap.js"></script>
     <h3>Standard Output</h3>