Add helper to login when typing User Agent

data/html/popup.html

@@ -23,8 +23,9 @@ <h1 class="center">Please Login</h1>
     <form id="user-agent-form" method="post" class="form">
       <input type="text" id="user-agent" placeholder="Please enter your wallet User Agent.">
       <button type="submit">Unlock</button>
+      <button type="button" id="login-whats-this">What's This?</a>
     </form>
-
+    
     <div class="errormsg" id="user-agent-error">
       There was an error logging in. Please check your password and try again.
     </div>

lib/js/popup.js

@@ -23,6 +23,10 @@ document.addEventListener('DOMContentLoaded', function () {
     }
   });
 
+  document.getElementById("login-whats-this").addEventListener("click", function () {
+      chrome.tabs.create({url: '/data/html/start.html'});
+  });
+
   // Login with valid User Agent
   document.getElementById('user-agent-form').addEventListener('submit', function (e) {
     e.preventDefault();