add `docker network prune`

`docker network prune` prunes unused networks, including overlay ones.
`docker system prune` also prunes unused networks.

Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>

docs/reference/commandline/container_prune.md

@@ -43,4 +43,5 @@ Total reclaimed space: 212 B
 * [system df](system_df.md)
 * [volume prune](volume_prune.md)
 * [image prune](image_prune.md)
+* [network prune](network_prune.md)
 * [system prune](system_prune.md)

docs/reference/commandline/image_prune.md

@@ -67,4 +67,5 @@ Total reclaimed space: 16.43 MB
 * [system df](system_df.md)
 * [container prune](container_prune.md)
 * [volume prune](volume_prune.md)
+* [network prune](network_prune.md)
 * [system prune](system_prune.md)

docs/reference/commandline/network_connect.md

@@ -98,5 +98,6 @@ You can connect a container to one or more networks. The networks need not be th
 * [network disconnect](network_disconnect.md)
 * [network ls](network_ls.md)
 * [network rm](network_rm.md)
+* [network prune](network_prune.md)
 * [Understand Docker container networks](https://docs.docker.com/engine/userguide/networking/)
 * [Work with networks](https://docs.docker.com/engine/userguide/networking/work-with-networks/)

docs/reference/commandline/network_create.md

@@ -197,4 +197,5 @@ to create an externally isolated `overlay` network, you can specify the
 * [network disconnect](network_disconnect.md)
 * [network ls](network_ls.md)
 * [network rm](network_rm.md)
+* [network prune](network_prune.md)
 * [Understand Docker container networks](https://docs.docker.com/engine/userguide/networking/)

docs/reference/commandline/network_disconnect.md

@@ -39,4 +39,5 @@ Disconnects a container from a network. The container must be running to disconn
 * [network create](network_create.md)
 * [network ls](network_ls.md)
 * [network rm](network_rm.md)
+* [network prune](network_prune.md)
 * [Understand Docker container networks](https://docs.docker.com/engine/userguide/networking/)

docs/reference/commandline/network_inspect.md

@@ -131,4 +131,5 @@ $ docker network inspect simple-network
 * [network create](network_create.md)
 * [network ls](network_ls.md)
 * [network rm](network_rm.md)
+* [network prune](network_prune.md)
 * [Understand Docker container networks](https://docs.docker.com/engine/userguide/networking/)

docs/reference/commandline/network_ls.md

@@ -214,4 +214,5 @@ d1584f8dc718: host
 * [network create](network_create.md)
 * [network inspect](network_inspect.md)
 * [network rm](network_rm.md)
+* [network prune](network_prune.md)
 * [Understand Docker container networks](https://docs.docker.com/engine/userguide/networking/)

docs/reference/commandline/network_prune.md

@@ -0,0 +1,45 @@
+---
+title: "network prune"
+description: "Remove unused networks"
+keywords: [network, prune, delete]
+---
+
+# network prune
+
+```markdown
+Usage:	docker network prune [OPTIONS]
+
+Remove all unused networks
+
+Options:
+  -f, --force   Do not prompt for confirmation
+      --help    Print usage
+```
+
+Remove all unused networks. Unused networks are those which are not referenced by any containers.
+
+Example output:
+
+```bash
+$ docker network prune
+WARNING! This will remove all networks not used by at least one container.
+Are you sure you want to continue? [y/N] y
+Deleted Networks:
+n1
+n2
+```
+
+## Related information
+
+* [network disconnect ](network_disconnect.md)
+* [network connect](network_connect.md)
+* [network create](network_create.md)
+* [network ls](network_ls.md)
+* [network inspect](network_inspect.md)
+* [network rm](network_rm.md)
+* [Understand Docker container networks](../../userguide/networking/index.md)
+* [system df](system_df.md)
+* [container prune](container_prune.md)
+* [image prune](image_prune.md)
+* [volume prune](volume_prune.md)
+* [system prune](system_prune.md)

docs/reference/commandline/network_rm.md

@@ -55,4 +55,5 @@ deletion.
 * [network create](network_create.md)
 * [network ls](network_ls.md)
 * [network inspect](network_inspect.md)
+* [network prune](network_prune.md)
 * [Understand Docker container networks](https://docs.docker.com/engine/userguide/networking/)

docs/reference/commandline/system_df.md

@@ -66,8 +66,11 @@ my-named-vol                                                       0
 * `UNIQUE SIZE` is the amount of space that is only used by a given image
 * `SIZE` is the virtual size of the image, it is the sum of `SHARED SIZE` and `UNIQUE SIZE`
 
+Note that network information is not shown because it doesn't consume the disk space.
+
 ## Related Information
 * [system prune](system_prune.md)
 * [container prune](container_prune.md)
 * [volume prune](volume_prune.md)
 * [image prune](image_prune.md)
+* [network prune](network_prune.md)

docs/reference/commandline/system_prune.md

@@ -26,7 +26,7 @@ Options:
       --help    Print usage
 ```
 
-Remove all unused containers, volumes and images (both dangling and unreferenced).
+Remove all unused containers, volumes, networks and images (both dangling and unreferenced).
 
 Example output:
 
@@ -35,6 +35,7 @@ $ docker system prune -a
 WARNING! This will remove:
 	- all stopped containers
 	- all volumes not used by at least one container
+	- all networks not used by at least one container
 	- all images without at least one container associated to them
 Are you sure you want to continue? [y/N] y
 Deleted Containers:
@@ -74,4 +75,5 @@ Total reclaimed space: 13.5 MB
 * [system df](system_df.md)
 * [container prune](container_prune.md)
 * [image prune](image_prune.md)
+* [network prune](network_prune.md)
 * [system prune](system_prune.md)

docs/reference/commandline/volume_prune.md

@@ -50,4 +50,5 @@ Total reclaimed space: 36 B
 * [system df](system_df.md)
 * [container prune](container_prune.md)
 * [image prune](image_prune.md)
+* [network prune](network_prune.md)
 * [system prune](system_prune.md)