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/config.toml.5.md

@@ -0,0 +1,130 @@
+# config.toml 5 02/02/2018
+
+## SYNOPSIS
+
+The **config.toml** file is a configuration file for the containerd daemon. The
+file must be placed in **/etc/containerd/** or used with the **--config**
+option of **containerd** to be used by the daemon. If the file does not exist
+at the appropriate location or is not provided via the **--config** option
+containerd uses its default configuration settings, which can be displayed
+with the **containerd config(1)** command.
+
+## DESCRIPTION
+
+The TOML file used to configure the containerd daemon settings has a short
+list of global settings followed by a series of sections for specific areas
+of daemon configuration. There is also a section for **plugins** that allows
+each containerd plugin to have an area for plugin-specific configuration and
+settings.
+
+## FORMAT
+
+**root**
+: The root directory for containerd metadata. (Default: "/var/lib/containerd")
+
+**state**
+: The state directory for containerd (Default: "/run/containerd")
+
+**oom_score**
+: The out of memory (OOM) score applied to the containerd daemon process (Default: 0)
+
+**[grpc]**
+: Section for gRPC socket listener settings. Contains three properties:
+ - **address** (Default: "/run/containerd/containerd.sock")
+ - **uid** (Default: 0)
+ - **gid** (Default: 0)
+
+**[debug]**
+: Section to enable and configure a debug socket listener. Contains four properties:
+ - **address** (Default: "/run/containerd/debug.sock")
+ - **uid** (Default: 0)
+ - **gid** (Default: 0)
+ - **level** (Default: "info") sets the debug log level
+
+**[metrics]**
+: Section to enable and configure a metrics listener. Contains two properties:
+ - **address** (Default: "") Metrics endpoint does not listen by default
+ - **grpc_histogram** (Default: false) Turn on or off gRPC histogram metrics
+
+**[cgroup]**
+: Section for Linux cgroup specific settings
+ - **path** (Default: "") Specify a custom cgroup path for created containers
+
+**[plugins]**
+: The plugins section contains configuration options exposed from installed plugins.
+The following plugins are enabled by default and their settings are shown below.
+Plugins that are not enabled by default will provide their own configuration values
+documentation.
+ - **[plugins.cgroup]** has one option __no_prometheus__ (Default: **false**)
+ - **[plugins.diff]** has one option __default__, a list by default set to **["walking"]**
+ - **[plugins.linux]** has several options for configuring the runtime, shim, and related options:
+   **shim** specifies the shim binary (Default: **"containerd-shim"**),
+   **runtime** is the OCI compliant runtime binary (Default: **"runc"**),
+   **runtime_root** is the root directory used by the runtime (Default: **""**),
+   **no_shim** specifies whether to use a shim or not (Default: **false**),
+   **shim_debug** turns on debugging for the shim (Default: **false**)
+ - **[plugins.scheduler]** has several options that perform advanced tuning for the scheduler:
+   **pause_threshold** is the maximum amount of time GC should be scheduled (Default: **0.02**),
+   **deletion_threshold** guarantees GC is scheduled after n number of deletions (Default: **0** [not triggered]),
+   **mutation_threshold** guarantees GC is scheduled after n number of database mutations (Default: **100**),
+   **schedule_delay** defines the delay after trigger event before scheduling a GC (Default **"0ms"** [immediate]),
+   **startup_delay** defines the delay after startup before scheduling a GC (Default **"100ms"**)
+
+## EXAMPLE
+
+The following is a complete **config.toml** default configuration example:
+
+```
+root = "/var/lib/containerd"
+state = "/run/containerd"
+oom_score = 0
+
+[grpc]
+  address = "/run/containerd/containerd.sock"
+  uid = 0
+  gid = 0
+
+[debug]
+  address = "/run/containerd/debug.sock"
+  uid = 0
+  gid = 0
+  level = "info"
+
+[metrics]
+  address = ""
+  grpc_histogram = false
+
+[cgroup]
+  path = ""
+
+[plugins]
+  [plugins.cgroups]
+    no_prometheus = false
+  [plugins.diff]
+    default = ["walking"]
+  [plugins.linux]
+    shim = "containerd-shim"
+    runtime = "runc"
+    runtime_root = ""
+    no_shim = false
+    shim_debug = false
+  [plugins.scheduler]
+    pause_threshold = 0.02
+    deletion_threshold = 0
+    mutation_threshold = 100
+    schedule_delay = 0
+    startup_delay = 100000000
+```
+
+## 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), containerd-config(1), containerd(1)