Use "none" instead of "null" for the null eventer

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

docs/libpod.conf.5.md

@@ -99,7 +99,7 @@ libpod to manage containers.
   a slirp4netns network.  If "" is used then the binary is looked up using the $PATH environment variable.
 
 **events_logger**=""
-  Default method to use when logging events. Valid values are "file", "journald", and "null".
+  Default method to use when logging events. Valid values are "file", "journald", and "none".
 
 **detach_keys**=""
   Keys sequence used for detaching a container

docs/podman.1.md

@@ -36,9 +36,9 @@ Note: CGroup manager is not supported in rootless mode when using CGroups Versio
 
 Path to where the cpu performance results should be written
 
-**--events-logger**=**type**
+**--events-logger**=*type*
 
-Backend to use for storing events. Allowed values are **file**, **journald**, and **null**.
+Backend to use for storing events. Allowed values are **file**, **journald**, and **none**.
 
 **--hooks-dir**=*path*
 

libpod/events/events.go

@@ -22,7 +22,7 @@ func (et EventerType) String() string {
 	case Journald:
 		return "journald"
 	case Null:
-		return "null"
+		return "none"
 	default:
 		return "invalid"
 	}

test/e2e/libpod_suite_test.go

@@ -74,7 +74,7 @@ func (p *PodmanTestIntegration) makeOptions(args []string, noEvents bool) []stri
 
 	eventsType := "file"
 	if noEvents {
-		eventsType = "null"
+		eventsType = "none"
 	}
 
 	podmanOptions := strings.Split(fmt.Sprintf("%s--root %s --runroot %s --runtime %s --conmon %s --cni-config-dir %s --cgroup-manager %s --tmpdir %s --events-backend %s",