mention about experimental protocols

diff --git a/doc/cha-intro-tls.texi b/doc/cha-intro-tls.texi
index 1e16a28fa9c225d37f3f60ff7466b4616050d03a..45f2fb028cc38d3f034201f67c26f0326beec404 100644 (file)
--- a/doc/cha-intro-tls.texi
+++ b/doc/cha-intro-tls.texi
@@ -637,6 +637,11 @@ string. To enable, use the following functions.
 
 @showfuncB{gnutls_alpn_set_protocols,gnutls_alpn_get_selected_protocol}
 
+Note that you can use these functions with protocols that are
+registered in the Application Layer Protocol Negotiation IANA registry.
+If you wish to use them for other custom protocols then prefix them
+with the 3 characters `exp' (lower-case).
+
 @include sec-tls-app.texi
 
 @node On SSL 2 and older protocols