Update README.md

Author: bdcoder2

README.md

@@ -23,7 +23,7 @@ This release includes support for <a href="https://developers.google.com/maps/do
   <li>Click on the &quot;Download&quot; button and save the archive locally.</li>
   <li>Un-zip the grid_clusterer archive</li>
   <li><b>IMPORTANT</b>: In order to use Google maps, you require a <a href="https://developers.google.com/maps/documentation/javascript/get-api-key">Google maps API key</a>.
-    <p>Replace the string &quot;<b>[YOUR_API_KEY]</b>&quot; with your Google maps API key in all "index.html" files found in the following directories:</p>
+    <p>Replace the string &quot;<b>[YOUR_API_KEY]</b>&quot; with your Google maps API key in all "index.html" files found in the following directories / files:</p>
     <ul>
       <li>./dist/ex0/index.html</li>
       <li>./dist/ex1/index.html</li>