feat: update forms instructions

closes: #1

content/forms/add.md

@@ -24,7 +24,11 @@ Forms can be added to websites with just the HTML code for it. For
 instance:
 
 ```html
-<form id="newsletter-form" method="POST">
+<form
+	id="newsletter-form"
+	method="POST"
+	action="https://<librepages-endpoint>/?path=<current-path>&host=<current-host>"
+>
 	<p>
 		Interested in receiving latest news about our cool product? Sign
 		up for you fantastic newsletter!
@@ -60,7 +64,8 @@ JavaScript code:
 	const form = document.getElementById("newsletter-form");
 
 	async function handleSubmit() {
-		const url = window.location;
+		const url =
+			"https://<librepages-endpoint>/api/v1/forms/submit?host=<current-host>&path=<current-path>";
 		const data = {
 			email: document.getElementById("email"),
 		};
@@ -77,4 +82,5 @@ JavaScript code:
 	form.addEventListener("submit", handleSubmit);
 </script>
 ```
+
 > Note: the following snippet also demonstrates JSON form submission