Update the HAProxy Docs URL

see https://www.mail-archive.com/haproxy@formilux.org/msg42790.html

Author: TimWolla

haproxy/content.md

@@ -10,7 +10,7 @@ HAProxy is a free, open source high availability solution, providing load balanc
 
 Since no two users of HAProxy are likely to configure it exactly alike, this image does not come with any default configuration.
 
-Please refer to [upstream's excellent (and comprehensive) documentation](https://cbonte.github.io/haproxy-dconv/) on the subject of configuring HAProxy for your needs.
+Please refer to [upstream's excellent (and comprehensive) documentation](https://docs.haproxy.org/) on the subject of configuring HAProxy for your needs.
 
 It is also worth checking out the [`examples/` directory from upstream](http://git.haproxy.org/?p=haproxy-2.3.git;a=tree;f=examples).