docs: Consistent typography for options of qemu-nbd

Prefer the :option:`--name` form when cross-referencing other options
from the qemu-nbd documentation.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20220314203818.3681277-2-eblake@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

docs/tools/qemu-nbd.rst

@@ -27,7 +27,7 @@ Options
 .. program:: qemu-nbd
 
 *filename* is a disk image filename, or a set of block
-driver options if ``--image-opts`` is specified.
+driver options if :option:`--image-opts` is specified.
 
 *dev* is an NBD device.
 
@@ -165,9 +165,9 @@ driver options if ``--image-opts`` is specified.
 .. option:: --tls-creds=ID
 
   Enable mandatory TLS encryption for the server by setting the ID
-  of the TLS credentials object previously created with the --object
-  option; or provide the credentials needed for connecting as a client
-  in list mode.
+  of the TLS credentials object previously created with the
+  :option:`--object` option; or provide the credentials needed for
+  connecting as a client in list mode.
 
 .. option:: --tls-hostname=hostname
 
@@ -176,11 +176,11 @@ driver options if ``--image-opts`` is specified.
   against information in the server provided certificate. Sometimes
   it might be required to override the hostname used to perform this
   check. For example, if the NBD client is using a tunnel from localhost
-  to connect to the remote server, the `--tls-hostname` option should
+  to connect to the remote server, the :option:`--tls-hostname` option should
   be used to set the officially expected hostname of the remote NBD
   server. This can also be used if accessing NBD over a UNIX socket
   where there is no inherent hostname available. This is only permitted
-  when acting as a NBD client with the `--list` option.
+  when acting as a NBD client with the :option:`--list` option.
 
 .. option:: --fork