curl_easy_unescape.3: update RFC reference

Reported-by: bsammon
Bug: https://github.com/bagder/curl/issues/282

docs/libcurl/curl_easy_unescape.3

@@ -5,7 +5,7 @@
 .\" *                            | (__| |_| |  _ <| |___
 .\" *                             \___|\___/|_| \_\_____|
 .\" *
-.\" * Copyright (C) 1998 - 2014, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
 .\" *
 .\" * This software is licensed as described in the file COPYING, which
 .\" * you should have received as part of this distribution. The terms
@@ -48,4 +48,4 @@ Added in 7.15.4 and replaces the old \fIcurl_unescape(3)\fP function.
 .SH RETURN VALUE
 A pointer to a zero terminated string or NULL if it failed.
 .SH "SEE ALSO"
-.BR curl_easy_escape "(3), " curl_free "(3)," RFC 2396
+.BR curl_easy_escape "(3), " curl_free "(3)," RFC 3986