A simple change - pre border using #f28d1a

Using the color #f28d1a plus look better , easier to read the code that is in black .

src/Packagist/WebBundle/Resources/public/css/main.css

@@ -37,7 +37,7 @@ pre, code {
     font-size: 12px;
 }
 pre {
-  border-left: 2px solid #2d2d32;
+  border-left: 2px solid #f28d1a;
 }
 code.hljs { display: inline; }