doc: document the non-portability of NONE priority string

Signed-off-by: Nikos Mavrogiannopoulos <nmav@gnutls.org>

1 files changed, 8 insertions, 1 deletions

diff --git a/doc/cha-gtls-app.texi b/doc/cha-gtls-app.texi
index 8de6c469b8..8fd31b2add 100644
--- a/doc/cha-gtls-app.texi
+++ b/doc/cha-gtls-app.texi
@@ -1183,7 +1183,14 @@ verification profile.
 
 @item NONE @tab
 Means nothing is enabled.  This disables even protocol versions.
-It should be followed by the algorithms to be enabled.
+It should be followed by the algorithms to be enabled. Note that
+using this option to build a priority string gives detailed control
+into the resulting settings, however it creates non-portable applications.
+With new revisions of the TLS protocol new priority items are routinely added
+requiring such a string to be continuously updated with the library. As
+such, we advice against using that option for applications targetting multiple versions
+of the GnuTLS library, and recommend using the defaults (see above) or
+adjusting the defaults via @funcref{gnutls_set_default_priority_append}.
 
 @end multitable
 @caption{Supported initial keywords.}