docs for labels on build, networks and volumes

Signed-off-by: Harald Albers <github@albersweb.de>

docs/reference/commandline/build.md

@@ -26,6 +26,7 @@ parent = "smn_cli"
       --force-rm                      Always remove intermediate containers
       --help                          Print usage
       --isolation=""                  Container isolation technology
+      --label=[]                      Set metadata for an image
       -m, --memory=""                 Memory limit for all build containers
       --memory-swap=""                A positive integer equal to memory plus swap. Specify -1 to enable unlimited swap.
       --no-cache                      Do not use cache when building the image

docs/reference/commandline/network_create.md

@@ -23,6 +23,7 @@ parent = "smn_cli"
     --ipam-driver=default    IP Address Management Driver
     --ipam-opt=map[]         Set custom IPAM driver specific options
     --ipv6                   Enable IPv6 networking
+    --label=[]               Set metadata on a network
     -o --opt=map[]           Set custom driver specific options
     --subnet=[]              Subnet in CIDR format that represents a network segment
 

docs/reference/commandline/volume_create.md

@@ -16,6 +16,7 @@ parent = "smn_cli"
 
       -d, --driver=local    Specify volume driver name
       --help                Print usage
+      --label=[]            Set metadata for a volume
       --name=               Specify volume name
       -o, --opt=map[]       Set driver specific options