Mandatory access control explainer

[dngray]

Description

Throughout the site we do make mention of SELinux, it comes up especially on Android and in the Redhat world.

I'm thinking we could some resources that are a "basic explainer" of what it is, and what it does. We could start with something lighthearted such as the SELinux Colouring Book.

It won't be an extensive "manual" as that could be very long, but rather a pointer to other resources. It could include reference to how to generate rulesets such as audit2allow and set specific values setsebool without disabling the whole thing.

We could include something about Apparmor here to, as that's often used on Debian based distributions and Archlinux and something about auditing and generating profiles there.