Merge pull request #1175 from ArthurHoaro/docs/apache-proxy-preserve-host

Include ProxyPreserveHost directive in Apache's proxy doc

doc/md/docker/reverse-proxy-configuration.md

@@ -13,12 +13,14 @@ This guide assumes that:
     - [mod_proxy](https://httpd.apache.org/docs/2.4/mod/mod_proxy.html)
     - [Reverse Proxy Request Headers](https://httpd.apache.org/docs/2.4/mod/mod_proxy.html#x-headers)
 
-The following HTTP headers are set by using the `ProxyPass` directive:
+The following HTTP headers are set when the `ProxyPass` directive is set:
 
 - `X-Forwarded-For`
 - `X-Forwarded-Host`
 - `X-Forwarded-Server`
 
+The original `SERVER_NAME` can be sent to the proxied host by setting the [`ProxyPreserveHost`](https://httpd.apache.org/docs/2.4/mod/mod_proxy.html#ProxyPreserveHost) directive to `On`.
+
 ```apache
 <VirtualHost *:80>
     ServerName shaarli.domain.tld
@@ -37,7 +39,8 @@ The following HTTP headers are set by using the `ProxyPass` directive:
     CustomLog /var/log/apache2/shaarli-access.log combined
 
     RequestHeader set X-Forwarded-Proto "https"
-
+    ProxyPreserveHost On
+    
     ProxyPass        / http://127.0.0.1:10080/
     ProxyPassReverse / http://127.0.0.1:10080/
 </VirtualHost>