Update 03-template-syntax.md

Added explanation on double event handlers that propagate to the parent. To make sure the developer understands the true power of adding multiple handlers. (and I have been in a situation forgetting about this, which took me a while to figure out).

site/content/docs/03-template-syntax.md

@@ -572,6 +572,13 @@ It's possible to have multiple event listeners for the same event:
 <button on:click={increment} on:click={track}>Click me!</button>
 ```
 
+But also this is possible:
+```sv
+<button on:click on:click>
+	This component  will emit the click event TWICE to its parent!!
+</button>
+```
+
 #### bind:*property*
 
 ```sv