Make a form validation handler | handle form messages

add "aria-describedby" attribute on "supported elements" section

add "aria-describedby" attribute on server side succeed validation messages

site/static/docs/5.2/assets/js/validate-forms.js

@@ -1,19 +0,0 @@
-// Example starter JavaScript for disabling form submissions if there are invalid fields
-(() => {
-  'use strict'
-
-  // Fetch all the forms we want to apply custom Bootstrap validation styles to
-  const forms = document.querySelectorAll('.needs-validation')
-
-  // Loop over them and prevent submission
-  Array.from(forms).forEach(form => {
-    form.addEventListener('submit', event => {
-      if (!form.checkValidity()) {
-        event.preventDefault()
-        event.stopPropagation()
-      }
-
-      form.classList.add('was-validated')
-    }, false)
-  })
-})()