man: move ctr.1, containerd-config to section 8, and fix generation

I missed this in my previous change: the ctr man page is also
in Section 8, because it's considered an administrative tool,
and containerd-config is related to containerd so updating these
as well.

This commit also fixes naming of the generated files, which was
hard-coded to .1.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

docs/man/containerd-config.8.md

@@ -0,0 +1,41 @@
+# containerd-config 8 01/30/2018
+
+## NAME
+
+containerd-config - information on the containerd config
+
+## 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 __containerd-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 __containerd-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(8), containerd(8), containerd-config.toml(5)