[PATCH v2 1/3] docs: Clarify NBD_REPLY_TYPE_ERROR lengths

[Eric Blake]

Add explicit mention that human-readable error message strings must
comply with the overall NBD string limits.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 doc/proto.md | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/doc/proto.md b/doc/proto.md
index 81ac755..bfebb5a 100644
--- a/doc/proto.md
+++ b/doc/proto.md
@@ -1824,7 +1824,9 @@ remaining structured fields at the end.
   be at least 6.  This chunk represents that an error occurred,
   and the client MAY NOT make any assumptions about partial
   success. This type SHOULD NOT be used more than once in a
-  structured reply.  Valid as a reply to any request.
+  structured reply.  Valid as a reply to any request.  Note that
+  *message length* MUST NOT exceed the 4096 bytes string length
+  limit.

   The payload is structured as:

-- 
2.35.1