Change welcome screen copy

// FREEBIE

options.html

@@ -11,7 +11,7 @@
     <div id='step1' class='step'>
       <img id='signal-icon' src='/images/icon_250.png'/>
       <div class='nav'>
-        <h1>Welcome to Signal for Chrome</h1>
+        <h1>Welcome to Signal Desktop</h1>
         <p>Privacy is possible. Signal makes it easy.</p>
         <div> <a class='button step2'>Get started</a> </div>
         <span class='dot step1 selected'></span>