Add basic manpages for ctr, containerd, containerd-config

Adds initial manpages for ctr, containerd, and containerd config
commands, as well as the config.toml configuration file.

Adds targets to Makefile for generating and installing manpages.

Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com>

docs/man/containerd-config.1.md

@@ -0,0 +1,37 @@
+# containerd-config 1 01/30/2018
+
+## SYNOPSIS
+
+containerd config [command]
+
+## DESCRIPTION
+
+The *containerd config* command has one subcommand, named *default*, which
+will display on standard output the default containerd config for this version
+of the containerd daemon.
+
+This output can be piped to a __config.toml(5)__ file and placed in
+**/etc/containerd** to be used as the configuration for containerd on daemon
+startup. The configuration can be placed in any filesystem location and used
+with the **--config** option to the containerd daemon as well.
+
+See __config.toml(5)__ for more information on the containerd configuration
+options.
+
+## OPTIONS
+
+**default**
+: This subcommand will output the TOML formatted containerd configuration to standard output
+
+## BUGS
+
+Please file any specific issues that you encounter at
+https://github.com/containerd/containerd.
+
+## AUTHOR
+
+Phil Estes <estesp@gmail.com>
+
+## SEE ALSO
+
+ctr(1), config.toml(5), containerd(1)