Socket: Remove \fixme item fixed in previous commit

Socket/ClientSocketHandle.hh

@@ -86,10 +86,6 @@ namespace senf {
 
         \see \ref policy_group \n
              \ref protocol_group
-
-        \fixme Add enable_if conditions so anything convertible to unsigned will not be interpreted
-            as a Range template argument but will use the unsigned variant of
-            read/readfrom/write/writeto.
       */
     template <class Policy>
     class ClientSocketHandle