added more links to our default html pages.

html/50x.html

@@ -16,6 +16,6 @@
 Please try again later.</p>
 <p>If you are the system administrator of this resource then you should check
 the <a href="http://nginx.org/r/error_log">error log</a> for details.</p>
-<p><em>Faithfully yours, OpenResty.</em></p>
+<p><em>Faithfully yours, [OpenResty](https://openresty.org/).</em></p>
 </body>
 </html>

html/index.html

@@ -20,6 +20,6 @@ working. Further configuration is required.</p>
 Commercial support is available at
 <a href="https://openresty.com/">openresty.com</a>.</p>
 
-<p><em>Thank you for flying OpenResty.</em></p>
+<p><em>Thank you for flying [OpenResty](https://openresty.org/).</em></p>
 </body>
 </html>