Add stub writeup for the userland

Signed-off-by: David Oberhollenzer <goliath@infraroot.at>

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+# Building a More Sophisticated Userspace
+
+After revisiting the structure of our `sysroot` directory, we will build
+and install some basic packages:
+
+* `tzdata`
+* `ncurses`
+* `readline`
+* `zlib`
+* `bash`
+* `bash-completion` scripts from Debian
+* `coreutils`
+* `diffutils`
+* `findutils`
+* `util-linux`
+* `grep`
+* `less`
+* `xz`
+* `gzip`
+* `bzip2`
+* `tar`
+* `sed`
+* `gawk`
+* `procps-ng`
+* `psmisc`
+* `file`
+* `shadow`
+* `inetutils`
+* `nano`
+* [gcron](https://github.com/pygos/cron)
+* [usyslog](https://github.com/pygos/usyslog)
+* [pygos init](https://github.com/pygos/init)
+* `init-scripts`
+
+Those should provide us with a pretty decent base system and GNU/Linux command
+line environment to work in. It's a lot of stuff, so I'd advise you to automate
+most of setps in some way using shell scripts. I will also provide some usefull
+utility functions below.
+
+I chose `nano` as text editor because it's dead simple to use. Furthermore, I
+used the init system from Pygos because it's configuration is a little more
+sophisticated and simpler than having to write dozens of shell scripts for a
+System V style init. Also, it requires basically no dependencies.
+
+Although networking is listed below, we need at least the `hostname` program
+from the `inetutils` package, so I added it to the list of the base system.
+
+After building this base system, we will again put it all together, i.e.
+package the whole thing into a SquashFS image, modify and rebuild the initrd,
+and take a closer look at the bootstrap processes through our `init` all the
+way to spawning `getty` instances on the console (remember, the goal here is
+to actually understand what's going on in the end).
+
+Once everything is working, we build a few more packages for wired networking:
+
+* `openssl`
+* `ldns`
+* `ntp`
+* `iana-etc`
+* `libmnl`
+* `libnftnl`
+* `gmp`
+* `iproute2`
+* `nftables`
+* `dhcpcd`
+* `libnl3`
+* `libpcup`
+* `tcpdump`
+* `openssh`
+
+We will modify the init scripts to obtain an IPv4 network configuration via
+DHCP on the wired Ethernet interface, configure basic firewalling
+through `nftables`, discussing a little bit of Linux network configuration
+and debugging along the way.
+
+An init script and a script for `dhcpcd` are added to fetch current date
+and time via `ntp`, since the Raspberry Pi does not have a real time clock
+on board.
+
+As a final step, we will take a look at setting up a wireless access point
+that NAT forwards traffic from its clients via the wired Ethernet port. This
+requires the following additional packages:
+
+* `libbsd`
+* `expat`
+* `unbound`
+* `dnsmasq`
+* `hostapd`
+* `iw`
+
+# TODO: write the remaining documentation