It's surprisingly good, overall, but there are some glaring omissions. For instance:

sudo apt-get install tree Only sudo is explained. I understand apt-get is distro-specific, but it's widespread enough to deserve a special case. Interestingly, apt-get install tree (without sudo) works better.

Common, widely known system configuration files like /etc/issue, /etc/hosts, /etc/hostname, /etc/fstab ... deserve to be special-cased, too. Many of them actually have their man pages, so it's possible to script.