Update SYS.rst (#5572)

Author: achimfritz

Documentation/Configuration/Typo3ConfVars/SYS.rst

@@ -397,7 +397,7 @@ configurations.
 
     :php:`*` or a list of IP addresses of proxies that use SSL (https) for
     the connection to the client, but an unencrypted connection (http) to
-    the server. If php:`*` all proxies defined in
+    the server. If :php:`*` all proxies defined in
     :ref:`[SYS][reverseProxyIP]<typo3ConfVars_sys_reverseProxyIP>` use SSL.
 
 ..  _typo3ConfVars_sys_reverseProxyPrefixSSL: