fix typo

Author: svgeesus

index.html

@@ -1413,7 +1413,7 @@ <h3>Introduction</h3>
         24-bit images and 8-bit transparency, which GIF lacks.</p>
 
         <p>APNG is backwards-compatible with earlier versions of PNG; a non-animated PNG decoder will ignore the ancillary
-        Apngific chunks and display the <a>static image</a>.</p>
+        APNG-specific chunks and display the <a>static image</a>.</p>
       </section>
 
       <section>