add some plugin manifest reference doc

Signed-off-by: Victor Vieux <vieux@docker.com>

docs/extend/index.md

@@ -151,7 +151,7 @@ drwxr-xr-x  3 root root 4096 Aug  8 17:56 cd851ce43a403
         "Capabilities": [
           "CAP_SYS_ADMIN"
         ],
-        "ManifestVersion": "v0.1",
+        "ManifestVersion": "v0",
         "Description": "sshFS plugin for Docker",
         "Documentation": "https://docs.docker.com/engine/extend/plugins/",
         "Interface": {
@@ -212,12 +212,12 @@ $ docker rmi rootfs
 ```
 
 `manifest.json` describes the plugin and `plugin-config.json` contains some
-runtime parameters. For example:
+runtime parameters. [See the Plugins Manifest reference](manifest.md). For example:
 
 ```bash
 # cat manifest.json
 {
-	"manifestVersion": "v0.1",
+	"manifestVersion": "v0",
 	"description": "sshFS plugin for Docker",
 	"documentation": "https://docs.docker.com/engine/extend/plugins/",
 	"entrypoint": ["/go/bin/docker-volume-sshfs"],

docs/extend/manifest.md

@@ -0,0 +1,222 @@
+<!--[metadata]>
++++
+aliases = [
+"/engine/extend/"
+]
+title = "Plugin manifest"
+description = "How develop and use a plugin with the managed plugin system"
+keywords = ["API, Usage, plugins, documentation, developer"]
+advisory = "experimental"
+[menu.main]
+parent = "engine_extend"
+weight=1
++++
+<![end-metadata]-->
+
+# Plugin Manifest Version 0 of Plugin V2
+
+This document outlines the format of the V0 plugin manifest. The plugin
+manifest described herein was introduced in the Docker daemon (experimental version) in the [v1.12.0
+release](https://github.com/docker/docker/commit/f37117045c5398fd3dca8016ea8ca0cb47e7312b).
+
+Plugin manifests describe the various constituents of a docker plugin. Plugin
+manifests can be serialized to JSON format with the following media types:
+
+Manifest Type  | Media Type
+------------- | -------------
+manifest  | "application/vnd.docker.plugin.v0+json"
+
+
+## *Manifest* Field Descriptions
+
+Manifest provides the base accessible fields for working with V0 plugin format
+ in the registry.
+
+- **`manifestVersion`** *string*
+
+	version of the plugin manifest (This version uses V0)
+
+- **`description`** *string*
+
+	description of the plugin
+
+- **`documentation`** *string*
+
+  	link to the documentation about the plugin
+
+- **`interface`** *PluginInterface*
+
+   interface implemented by the plugins, struct consisting of the following fields
+      
+    - **`types`** *string array*
+
+      types indicate what interface(s) the plugin currently implements.
+
+      currently supported:
+
+      	- **docker.volumedriver/1.0**
+      
+    - **`socket`** *string*
+      
+      socket is the name of the socket the engine should use to communicate with the plugins.
+      the socket will be created in `/run/docker/plugins`.
+
+
+- **`entrypoint`** *string array*
+
+   entrypoint of the plugin, see [`ENTRYPOINT`](../reference/builder.md#entrypoint)
+
+- **`workdir`** *string*
+
+   workdir of the plugin, see [`WORKDIR`](../reference/builder.md#workdir)
+
+- **`network`** *PluginNetwork*
+
+   network of the plugin, struct consisting of the following fields
+      
+    - **`type`** *string*
+
+      network type.
+
+      currently supported:
+
+      	- **bridge**
+      	- **host**
+      	- **none**
+      
+- **`capabilities`** *array*
+
+   capabilities of the plugin (*Linux only*), see list [`here`](https://github.com/opencontainers/runc/blob/master/libcontainer/SPEC.md#security)
+    
+- **`mounts`** *PluginMount array*
+
+   mount of the plugin, struct consisting of the following fields, see [`MOUNTS`](https://github.com/opencontainers/runtime-spec/blob/master/config.md#mounts)
+
+    - **`name`** *string*
+
+	  name of the mount.
+      
+    - **`description`** *string*
+	
+      description of the mount.
+   
+    - **`source`** *string*
+
+	  source of the mount.
+    
+    - **`destination`** *string*
+
+	  destination of the mount.
+   
+    - **`type`** *string*
+
+      mount type.
+      
+    - **`options`** *string array*
+
+	  options of the mount.
+      
+- **`devices`** *PluginDevice array*
+
+    device of the plugin, (*Linux only*), struct consisting of the following fields, see [`DEVICES`](https://github.com/opencontainers/runtime-spec/blob/master/config-linux.md#devices)
+
+    - **`name`** *string*
+
+	  name of the device.
+      
+    - **`description`** *string*
+
+      description of the device.
+      
+    - **`path`** *string*
+
+	  path of the device.
+
+- **`env`** *PluginEnv array*
+
+   env of the plugin, struct consisting of the following fields
+
+    - **`name`** *string*
+
+	  name of the env.
+      
+    - **`description`** *string*
+	
+      description of the env.
+   
+    - **`value`** *string*
+
+	  value of the env.
+    
+- **`args`** *PluginArgs*
+
+   args of the plugin, struct consisting of the following fields
+
+    - **`name`** *string*
+
+	  name of the env.
+      
+    - **`description`** *string*
+	
+      description of the env.
+   
+    - **`value`** *string array*
+
+	  values of the args.
+    
+    
+## Example Manifest
+
+*Example showing the 'tiborvass/no-remove' plugin manifest.*
+
+```
+{
+       	"manifestVersion": "v0",
+       	"description": "A test plugin for Docker",
+       	"documentation": "https://docs.docker.com/engine/extend/plugins/",
+       	"entrypoint": ["plugin-no-remove", "/data"],
+       	"interface" : {
+       		"types": ["docker.volumedriver/1.0"],
+       		"socket": "plugins.sock"
+       	},
+       	"network": {
+       		"type": "host"
+       	},
+
+       	"mounts": [
+       		{
+       			"source": "/data",
+       			"destination": "/data",
+       			"type": "bind",
+       			"options": ["shared", "rbind"]
+       		},
+       		{
+       			"destination": "/foobar",
+       			"type": "tmpfs"
+       		}
+       	],
+
+       	"args": {
+       		"name": "args",
+       		"description": "command line arguments",
+       		"value": []
+       	},
+
+       	"env": [
+       		{
+       			"name": "DEBUG",
+       			"description": "If set, prints debug messages",
+       			"value": "1"
+       		}
+       	],
+
+       	"devices": [
+       		{
+       			"name": "device",
+       			"description": "a host device to mount",
+       			"path": "/dev/cpu_dma_latency"
+       		}
+       	]
+}
+
+```