correct prompt for story selection

Author: Lidaron

earthlapse-hci/modes-menu.html

@@ -73,7 +73,7 @@
     <h1>Welcome to Planet Earth!</h1>
 
     <section class="earthlapse-modes-menu-section earthlapse-modes-menu-section-stories">
-        <h2 class="earthlapse-modes-menu-section-heading">Choose a story to begin</h2>
+        <h2 class="earthlapse-modes-menu-section-heading">Choose a story</h2>
 
         <div class="earthlapse-stories-gallery">
             <!-- Todo: Columbia Glacier -->