Update varlink doc and code

* Improved error message
* Added documentation
* Updated messages to include missing data

Signed-off-by: Jhon Honce <jhonce@redhat.com>

cmd/podman/shared/create.go

@@ -81,7 +81,7 @@ func CreateContainer(ctx context.Context, c *GenericCLIResults, runtime *libpod.
 		if len(c.InputArgs) != 0 {
 			name = c.InputArgs[0]
 		} else {
-			return nil, nil, errors.Errorf("error, no input arguments were provided")
+			return nil, nil, errors.Errorf("error, image name not provided")
 		}
 
 		pullType, err := util.ValidatePullType(c.String("pull"))

cmd/podman/varlink/io.podman.varlink

@@ -274,6 +274,8 @@ type Sockets(
 )
 
 # Create is an input structure for creating containers.
+# args[0] is the image name or id
+# args[1-] are the new commands if changed
 type Create (
     args: []string,
     addHost: ?[]string,
@@ -1281,4 +1283,4 @@ error WantsMoreRequired (reason: string)
 error ErrCtrStopped (id: string)
 
 # This function requires CGroupsV2 to run in rootless mode.
-error ErrRequiresCgroupsV2ForRootless(reason: string)
+error ErrRequiresCgroupsV2ForRootless(reason: string)