Add filter for network ls to hide predefined net

Add filter support for `network ls` to hide predefined network,
then user can use "docker network rm `docker network ls -f type=custom`"
to delete a bundle of userdefined networks.

Signed-off-by: Zhang Wei <zhangwei555@huawei.com>

docs/reference/commandline/network_ls.md

@@ -13,6 +13,7 @@ parent = "smn_cli"
     Usage:  docker network ls [OPTIONS]
 
     Lists all the networks created by the user
+      -f, --filter=[]       Filter output based on conditions provided
       --help=false          Print usage
       --no-trunc=false      Do not truncate the output
       -q, --quiet=false     Only display numeric IDs
@@ -38,8 +39,91 @@ NETWORK ID                                                         NAME
 c288470c46f6c8949c5f7e5099b5b7947b07eabe8d9a27d79a9cbf111adcbf47   host                host                
 7b369448dccbf865d397c8d2be0cda7cf7edc6b0945f77d2529912ae917a0185   bridge              bridge              
 95e74588f40db048e86320c6526440c504650a1ff3e9f7d60a497c4d2163e5bd   foo                 bridge    
+63d1ff1f77b07ca51070a8c227e962238358bd310bde1529cf62e6c307ade161   dev                 bridge
 ```
 
+## Filtering
+
+The filtering flag (`-f` or `--filter`) format is a `key=value` pair. If there
+is more than one filter, then pass multiple flags (e.g. `--filter "foo=bar" --filter "bif=baz"`).
+Multiple filter flags are combined as an `OR` filter. For example, 
+`-f type=custom -f type=builtin` returns both `custom` and `builtin` networks.
+
+The currently supported filters are:
+
+* id (network's id)
+* name (network's name)
+* type (custom|builtin)
+
+#### Type
+
+The `type` filter supports two values; `builtin` displays predefined networks
+(`bridge`, `none`, `host`), whereas `custom` displays user defined networks.
+
+The following filter matches all user defined networks:
+
+```bash
+$ docker network ls --filter type=custom
+NETWORK ID          NAME                DRIVER
+95e74588f40d        foo                 bridge
+63d1ff1f77b0        dev                 bridge
+```
+
+By having this flag it allows for batch cleanup. For example, use this filter
+to delete all user defined networks:
+
+```bash
+$ docker network rm `docker network ls --filter type=custom -q`
+```
+
+A warning will be issued when trying to remove a network that has containers
+attached.
+
+#### Name
+
+The `name` filter matches on all or part of a network's name.
+
+The following filter matches all networks with a name containing the `foobar` string.
+
+```bash
+$ docker network ls --filter name=foobar
+NETWORK ID          NAME                DRIVER
+06e7eef0a170        foobar              bridge
+```
+
+You can also filter for a substring in a name as this shows:
+
+```bash
+$ docker ps --filter name=foo
+NETWORK ID          NAME                DRIVER
+95e74588f40d        foo                 bridge
+06e7eef0a170        foobar              bridge
+```
+
+#### ID
+
+The `id` filter matches on all or part of a network's ID.
+
+The following filter matches all networks with a name containing the
+`06e7eef01700` string.
+
+```bash
+$ docker network ls --filter id=63d1ff1f77b07ca51070a8c227e962238358bd310bde1529cf62e6c307ade161
+NETWORK ID          NAME                DRIVER
+63d1ff1f77b0        dev                 bridge
+```
+
+You can also filter for a substring in a ID as this shows:
+
+```bash
+$ docker ps --filter id=95e74588f40d
+NETWORK ID          NAME                DRIVER
+95e74588f40d        foo                 bridge
+
+$ docker ps --filter id=95e
+NETWORK ID          NAME                DRIVER
+95e74588f40d        foo                 bridge
+```
 
 ## Related information