apt package which contain
apt-get, also contains the manpage for
apt-get (it even contains it in 7 languages), so if you have
apt-get installed, you really should have the manpage. If you don't you've messed up your system in a way beyond what any packaging system can help you with.
Similar can be said for
mkdir in the
coreutils package, and for
But configuring APT to not install recommends (which I also always do, and believe to be a good thing), will mean that you don't get manpages of any program where the Debian developer making the package has chosen not to include it in the package, but in a package that is only a recommandation. I guess there's a lot of options, but some number of programs have manpages in the