doc: Typo fix on baseline implementation
authorEric Blake <eblake@redhat.com>
Fri, 29 Jul 2022 21:16:44 +0000 (16:16 -0500)
committerEric Blake <eblake@redhat.com>
Fri, 29 Jul 2022 21:16:44 +0000 (16:16 -0500)
commita6f392baaa833c6904de0b9b3dfaa81ce5fd24c6
tree9e9230b42508f4350f8b09e575bc22396388aa65
parent15cac433346613a73cb3c290d9c31114c02086ae
doc: Typo fix on baseline implementation

The server replies to NBD_OPT_ with NBD_RET_; there is no
NBD_OPT_UNSUP.

Fixes: 7827f3ae ("Add initial baseline/maximum interop spec", v3.20)
doc/proto.md