Changes "Android build" on the downloads page to "Google Play Store build"

Clears up some confusion surrounding the fact that the Canary and Nightly builds also have Android builds for download now.

site/content/download.md

@@ -87,7 +87,7 @@ The Citra updater provides a easy interface to install, update and manage Citra.
 </table>
 <div style="text-align: center; padding: 0px; margin: 0px;"><a href = "https://github.com/citra-emu/citra-canary/releases">Click here to view previous versions...</a></div>
 
-<h3>Android Build <span style='font-size: smaller; margin-left: 6px;'> Last release was  <span id='last-updated-android'></span></span></h3>
+<h3>Google Play Store Build <span style='font-size: smaller; margin-left: 6px;'> Last release was  <span id='last-updated-android'></span></span></h3>
 <table id="downloads-android" class="table">
     <thead>
         <tr>