Add the list of possible values for --log-level to help text

Closes #10034

Signed-off-by: Doug Davis <dug@us.ibm.com>

docker/flags.go

@@ -33,7 +33,7 @@ var (
 	flDaemon      = flag.Bool([]string{"d", "-daemon"}, false, "Enable daemon mode")
 	flDebug       = flag.Bool([]string{"D", "-debug"}, false, "Enable debug mode")
 	flSocketGroup = flag.String([]string{"G", "-group"}, "docker", "Group to assign the unix socket specified by -H when running in daemon mode\nuse '' (the empty string) to disable setting of a group")
-	flLogLevel    = flag.String([]string{"l", "-log-level"}, "info", "Set the logging level")
+	flLogLevel    = flag.String([]string{"l", "-log-level"}, "info", "Set the logging level (debug, info, warn, error, fatal)")
 	flEnableCors  = flag.Bool([]string{"#api-enable-cors", "-api-enable-cors"}, false, "Enable CORS headers in the remote API")
 	flTls         = flag.Bool([]string{"-tls"}, false, "Use TLS; implied by --tlsverify flag")
 	flHelp        = flag.Bool([]string{"h", "-help"}, false, "Print usage")

docs/man/docker.1.md

@@ -76,7 +76,7 @@ unix://[/path/to/socket] to use.
 **--ipv6**=*true*|*false*
   Enable IPv6 support. Default is false. Docker will create an IPv6-enabled bridge with address fe80::1 which will allow you to create IPv6-enabled containers. Use together with `--fixed-cidr-v6` to provide globally routable IPv6 addresses. IPv6 forwarding will be enabled if not used with `--ip-forward=false`. This may collide with your host's current IPv6 settings. For more information please consult the documentation about "Advanced Networking - IPv6".
 
-**-l**, **--log-level**="*debug*|*info*|*error*|*fatal*""
+**-l**, **--log-level**="*debug*|*info*|*warn*|*error*|*fatal*""
   Set the logging level. Default is `info`.
 
 **--label**="[]"

docs/sources/reference/commandline/cli.md

@@ -92,7 +92,7 @@ expect an integer, and they can only be specified once.
       --ip-masq=true                             Enable IP masquerading for bridge's IP range
       --iptables=true                            Enable Docker's addition of iptables rules
       --ipv6=false                               Enable Docker IPv6 support
-       -l, --log-level="info"                    Set the logging level
+       -l, --log-level="info"                    Set the logging level (debug, info, warn, error, fatal)
       --label=[]                                 Set key=value labels to the daemon (displayed in `docker info`)
       --mtu=0                                    Set the containers network MTU
                                                    if no value is provided: default to the default route MTU or 1500 if no default route is available