feedback: more strict confirmance language

Correct new language to explicitly use MAY/SHOULD/MUST
or simply drop the somewhat vague "can" where
we are describing the only way to operate the device.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
feedback: more verbose text re next entry

It's not immediately obvious what does next entry
refer to. Make this explicit.

Cc: Arun Subbarao <asubbarao@lnxw.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
feedback: minor wording cleanups

We already mention requirement for natural width
accesses for non device specific configuration.
Don't repeat this in legacy section.

Further, mention virtio pci structure in
preamble to help link sections together.

Cc: Arun Subbarao <asubbarao@lnxw.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Conflicts:
	content.tex
PCI: better document driver and device requirements

Feedback:
10) 4.1.3.1.2 Queue Vector Configuration
Some of the information from section 8.4 needs to be moved to
here, for example that the device may have an MSI-X table size
other than 2048.
Otherwise, this reads as though the MSI-X table must always have
2048 entries.

11) Please explicitly describe the device behavior when writing
a vector value beyond the MSI-X table size.

Address these comments.

Cc: Arun Subbarao <asubbarao@lnxw.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>