Punctuation fixes in “Client-side form validation” code comments (#5597)

Made punctuation changes to end of line comments (inserted commas) starting
in line 588. No code changes were made.

files/en-us/learn/forms/form_validation/index.html

@@ -585,15 +585,15 @@ <h4 id="A_more_detailed_example">A more detailed example</h4>
 
 function showError() {
   if(email.validity.valueMissing) {
-    // If the field is empty
+    // If the field is empty,
     // display the following error message.
     emailError.textContent = 'You need to enter an e-mail address.';
   } else if(email.validity.typeMismatch) {
-    // If the field doesn't contain an email address
+    // If the field doesn't contain an email address,
     // display the following error message.
     emailError.textContent = 'Entered value needs to be an e-mail address.';
   } else if(email.validity.tooShort) {
-    // If the data is too short
+    // If the data is too short,
     // display the following error message.
     emailError.textContent = `Email should be at least ${ email.minLength } characters; you entered ${ email.value.length }.`;
   }