documented writeinfo as removed in 7.4

docs/curl_easy_setopt.3

@@ -330,6 +330,7 @@ will be used. Set the string to NULL to disable kerberos4. The kerberos
 support only works for FTP. (Added in libcurl 7.3)
 .TP
 .B CURLOPT_WRITEINFO
+(NOT PRESENT IN 7.4 or later!)
 Pass a pointer to a zero terminated string as parameter. It will be used to
 report information after a successful request. This string may contain
 variables that will be substituted by their contents when output. Described