Fix documentation of oci: and oci-archive:

Fixes confusion reported in containers/podman#11553 .

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

docs/containers-transports.5.md

@@ -57,12 +57,12 @@ An image stored in the docker daemon's internal storage.
 The image must be specified as a _docker-reference_ or in an alternative _algo:digest_ format when being used as an image source.
 The _algo:digest_ refers to the image ID reported by docker-inspect(1).
 
-### **oci:**_path[:tag]_
+### **oci:**_path[:reference]_
 
 An image compliant with the "Open Container Image Layout Specification" at _path_.
-Using a _tag_ is optional and allows for storing multiple images at the same _path_.
+Using a _reference_ is optional and allows for storing multiple images at the same _path_.
 
-### **oci-archive:**_path[:tag]_
+### **oci-archive:**_path[:reference]_
 
 An image compliant with the "Open Container Image Layout Specification" stored as a tar(1) archive at _path_.