Update docs+messages to reflect uidmaps/gidmaps code

Signed-off-by: Jason Chua <jasonc1804@gmail.com>

Author: jasonchuanet

docs/Extensions.md

@@ -7,9 +7,9 @@ are generally specified under fields with "x-podman" prefix in the compose file.
 
 The following extension keys are available under container configuration:
 
-* `x-podman.uidmap` - Run the container in a new user namespace using the supplied UID mapping.
+* `x-podman.uidmaps` - Run the container in a new user namespace using the supplied UID mapping.
 
-* `x-podman.gidmap` - Run the container in a new user namespace using the supplied GID mapping.
+* `x-podman.gidmaps` - Run the container in a new user namespace using the supplied GID mapping.
 
 * `x-podman.rootfs` - Run the container without requiring any image management; the rootfs of the
 container is assumed to be managed externally.

podman_compose.py

@@ -1239,8 +1239,8 @@ async def container_to_args(compose, cnt, detached=True):
     # handle podman extension
     if 'x-podman' in cnt:
         raise ValueError(
-            'Configuration under x-podman has been migrated to x-podman.uidmap and '
-            'x-podman.gidmap fields'
+            'Configuration under x-podman has been migrated to x-podman.uidmaps and '
+            'x-podman.gidmaps fields'
         )
 
     rootfs_mode = False