update related to nginx/apache proxy configs

DOCUMENTATION.md

@@ -338,11 +338,16 @@ removed from the example below.
 
 Example **nginx** configuration:
 
+See for latest examples: https://github.com/Kozea/Radicale/tree/master/contrib/nginx/
+
 ```nginx
 location /radicale/ { # The trailing / is important!
     proxy_pass        http://localhost:5232/; # The / is important!
     proxy_set_header  X-Script-Name /radicale;
     proxy_set_header  X-Forwarded-For $proxy_add_x_forwarded_for;
+    proxy_set_header  X-Forwarded-Host $host;
+    proxy_set_header  X-Forwarded-Port $server_port;
+    proxy_set_header  X-Forwarded-Proto $scheme;
     proxy_set_header  Host $http_host;
     proxy_pass_header Authorization;
 }
@@ -361,6 +366,8 @@ handle_path /radicale/* {
 
 Example **Apache** configuration:
 
+See for latest examples: https://github.com/Kozea/Radicale/tree/master/contrib/apache/
+
 ```apache
 RewriteEngine On
 RewriteRule ^/radicale$ /radicale/ [R,L]
@@ -370,10 +377,7 @@ RewriteRule ^/radicale$ /radicale/ [R,L]
     ProxyPassReverse http://localhost:5232/
     RequestHeader    set X-Script-Name /radicale
     RequestHeader    set X-Forwarded-Port "%{SERVER_PORT}s"
-    RequestHeader    unset X-Forwarded-Proto
-    <If "%{HTTPS} =~ /on/">
-    RequestHeader    set X-Forwarded-Proto "https"
-    </If>
+    RequestHeader    set X-Forwarded-Proto expr=%{REQUEST_SCHEME}
 </Location>
 ```