fix highlightjs bug with code block

We should distinguish <code> and <pre><code>.

Signed-off-by: Le Tan <[email protected]>

src/resources/pre_template.html

@@ -26,7 +26,9 @@
 
       var codes = document.getElementsByTagName('code');
       for (var i = 0; i < codes.length; ++i) {
-          hljs.highlightBlock(codes[i]);
+          if (codes[i].parentElement.tagName.toLowerCase() == 'pre') {
+              hljs.highlightBlock(codes[i]);
+          }
       }
   }