Prevent submitting the demo form (#272)

* Prevent submitting the demo form

When the submit button on the demo form is pressed, the form is actually
submitted and the page is refreshed.

Let's prevent the form from submitting by adding a dummy onsubmit
handler that returns false.

* Create hungry-eagles-shout.md

Co-authored-by: Kognise <felix.mattick@gmail.com>

.changeset/hungry-eagles-shout.md

@@ -0,0 +1,5 @@
+---
+"water.css": patch
+---
+
+Prevent submitting the demo form