[libsoup/mcatanzaro/#184: 4/4] negotiate: add link to RFC 4559

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 35eea020b61be59695de3324f6a29dcfc9e9c267
Author: Michael Catanzaro <mcatanzaro redhat com>
Date:   Wed May 4 16:00:28 2022 -0500

    negotiate: add link to RFC 4559
    
    Understanding that RFC 4559 exists would help anybody reading the API
    docs, and also anybody working on this file.

 libsoup/auth/soup-auth-negotiate.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/libsoup/auth/soup-auth-negotiate.c b/libsoup/auth/soup-auth-negotiate.c
index 1c938aaf..c5567bba 100644
--- a/libsoup/auth/soup-auth-negotiate.c
+++ b/libsoup/auth/soup-auth-negotiate.c
@@ -80,7 +80,8 @@ typedef struct {
 /**
  * SoupAuthNegotiate:
  *
- * HTTP-based GSS-Negotiate authentication.
+ * HTTP-based GSS-Negotiate authentication, as defined by
+ * [RFC 4559](https://datatracker.ietf.org/doc/html/rfc4559).
  *
  * [class@Session]s do not support this type by default; if you want to
  * enable support for it, call [method@Session.add_feature_by_type],