update missed paragraph referencing Android version

static/features.html

@@ -147,7 +147,7 @@ <h2><a href="#table-of-contents">Table of contents</a></h2>
             <section id="grapheneos">
                 <h2><a href="#grapheneos">GrapheneOS</a></h2>
 
-                <p>These are the features of GrapheneOS beyond what's provided by version 14 of
+                <p>These are the features of GrapheneOS beyond what's provided by version 15 of
                 the Android Open Source Project. It only covers our improvements to AOSP and not
                 baseline features. This section doesn't list features like the standard app
                 sandbox, verified boot, exploit mitigations (ASLR, SSP, Shadow Call Stack, Control