A lot of our content dirs had links to master when they shouldn't have.
These are now replaced with local links.
Signed-off-by: Nic Cope <nicc@rk0n.org>
While we're here, move the common content on matching and debugging to their own
top-level headings, since they apply to all the different ImageConfig features.
Signed-off-by: Adam Wolfe Gordon <awg@upbound.io>