added username suggestions in en-US

Author: ygonz174

public/language/en-GB/error.json

@@ -38,7 +38,7 @@
 
 	"invalid-pagination-value": "Invalid pagination value, must be at least %1 and at most %2",
 
-	"username-taken": "Username taken",
+	"username-taken": "Username taken. Maybe try %1",
 	"email-taken": "Email address is already taken.",
 	"email-nochange": "The email entered is the same as the email already on file.",
 	"email-invited": "Email was already invited",

public/language/en-US/error.json

@@ -32,7 +32,7 @@
     "invalid-path": "Invalid path",
     "folder-exists": "Folder exists",
     "invalid-pagination-value": "Invalid pagination value, must be at least %1 and at most %2",
-    "username-taken": "Username taken",
+    "username-taken": "Username taken. Maybe try %1",
     "email-taken": "Email address is already taken.",
     "email-nochange": "The email entered is the same as the email already on file.",
     "email-invited": "Email was already invited",

public/src/client/register.js

@@ -121,6 +121,7 @@ define('forum/register', [
 		username_notify.text('');
 		const usernameInput = $('#username');
 		const userslug = slugify(username);
+		
 		if (username.length < ajaxify.data.minimumUsernameLength || userslug.length < ajaxify.data.minimumUsernameLength) {
 			showError(usernameInput, username_notify, '[[error:username-too-short]]');
 		} else if (username.length > ajaxify.data.maximumUsernameLength) {
@@ -135,14 +136,15 @@ define('forum/register', [
 				if (results.every(obj => obj.status === 'rejected')) {
 					showSuccess(usernameInput, username_notify, successIcon);
 				} else {
-					showError(usernameInput, username_notify, '[[error:username-taken]]');
+					// This is the specific block we are changing
+					const suggestedUsername = username + 'suffix';
+					showError(usernameInput, username_notify, '[[error:username-taken, ' + suggestedUsername + ']]');
 				}
 
 				callback();
 			});
 		}
 	}
-
 	function validatePassword(password, password_confirm) {
 		const passwordInput = $('#password');
 		const password_notify = $('#password-notify');