Update wording about app pricing

docs/index.html

@@ -127,10 +127,13 @@ <h2>Is the App Free?</h2>
             </p>
             <p>
                 The app is available through the Google Play Store. This
-                method is not free, however. This is both to support
-                development and to offset the additional work required
-                to work with Google. Updates through this method may be
-                slower and less reliable.
+                method is not free, however. Installing apps through
+                the Play Store is not recommended, as they can be slower, less
+                functional and less reliable to update than a direct install.
+                Supporting the Play Store requires enough extra development
+                effort that takes time away from developing other software, and
+                so the price of this installation method will continue to
+                increase over time to reflect that effort.
             </p>
         </article>
         <article>