Edited titlepage.html with Atlas code editor

Author: aantonop

titlepage.html

@@ -1,6 +1,6 @@
 <section data-type="titlepage">
 <h1>Mastering Ethereum</h1>
 <p class="edition">First Edition</p>
-<p class="subtitle">Building Smart Contracts & DApps</p>
+<p class="subtitle">Building Smart Contracts and DApps</p>
 <p class="author">Andreas M. Antonopoulos, Gavin Wood</p>
 </section>