v2v: Chapter 3 done

Signed-off-by: May <sirhuntthepure@users.noreply.github.com>
v2v: fix two xref TODOs

Signed-off-by: May <sirhuntthepure@users.noreply.github.com>
v2v: fix example id in chapter 4

Signed-off-by: May <sirhuntthepure@users.noreply.github.com>