doc/go1.7.html: don't mention obsolete RFC

Change-Id: Ia978c10a97e4c24fd7cf1fa4a7c3bd886d20bbf8
Reviewed-on: https://go-review.googlesource.com/24241Reviewed-by: Andrew Gerrand <adg@golang.org>

doc/go1.7.html

@@ -857,7 +857,7 @@ status <code>005</code>, not just <code>5</code>.
 
 <p>
 The server implementation now correctly sends only one "Transfer-Encoding" header when "chunked"
-is set explicitly, following <a href="https://tools.ietf.org/html/rfc2616#section-3.6">RFC 2616</a>.
+is set explicitly, following <a href="https://tools.ietf.org/html/rfc7230#section-3.3.1">RFC 7230</a>.
 </p>
 
 <p>