[6.0] 443c4401c Clarify what Debug means

[Dridi Boukelmoune]

commit 443c4401c168f4922edde3cabb48619d0fd4e207
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Mon Sep 17 11:03:17 2018 +0200

    Clarify what Debug means

diff --git a/include/tbl/vsl_tags.h b/include/tbl/vsl_tags.h
index 6e7b81031..85a480e7b 100644
--- a/include/tbl/vsl_tags.h
+++ b/include/tbl/vsl_tags.h
@@ -51,6 +51,8 @@ SLTM(Debug, SLT_F_UNSAFE, "Debug messages",
 	"Debug messages can normally be ignored, but are sometimes"
 	" helpful during trouble-shooting.  Most debug messages must"
 	" be explicitly enabled with parameters.\n\n"
+	"Debug messages may be added, changed or removed without"
+	" prior notice and shouldn't be considered stable.\n\n"
 )
 
 SLTM(Error, 0, "Error messages",