update Apache reverse proxy documentation to be aligned with destination check of MOVE request

DOCUMENTATION.md

@@ -354,6 +354,10 @@ RewriteRule ^/radicale$ /radicale/ [R,L]
     ProxyPass        http://localhost:5232/ retry=0
     ProxyPassReverse http://localhost:5232/
     RequestHeader    set X-Script-Name /radicale
+    RequestHeader    set X-Forwarded-Port "%{SERVER_PORT}s"
+    <If "%{HTTPS} =~ /on/">
+    RequestHeader    set X-Forwarded-Proto "https"
+    </If>
 </Location>
 ```
 
@@ -366,6 +370,10 @@ RewriteRule ^(.*)$ http://localhost:5232/$1 [P,L]
 
 # Set to directory of .htaccess file:
 RequestHeader set X-Script-Name /radicale
+RequestHeader set X-Forwarded-Port "%{SERVER_PORT}s"
+<If "%{HTTPS} =~ /on/">
+RequestHeader set X-Forwarded-Proto "https"
+</If>
 ```
 
 Be reminded that Radicale's default configuration enforces limits on the