Although individual qemu-storage-daemon QMP commands are identical to
QEMU QMP commands, qemu-storage-daemon only supports a subset of QEMU's
QMP commands. Generate a manual page of just the commands supported by
qemu-storage-daemon so that users know exactly what is available in
qemu-storage-daemon.

Add an h1 heading in storage-daemon/qapi/qapi-schema.json so that
block-core.json is at the h2 heading level.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20201209103802.350848-2-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>