README: use local storage by default

Pulling container images into local storage is the new default behaviour
for `bootc-image-builder`. The README is updated to reflect this and
to explain how to achieve the previous default.

README.md

@@ -31,29 +31,6 @@ by adding a volume-mount for the local file as well as the `--config` flag to th
 
 The following command will create a QCOW2 disk image. First, create `./config.json` as described above to configure user access.
 
-```bash
-sudo podman run \
-    --rm \
-    -it \
-    --privileged \
-    --pull=newer \
-    --security-opt label=type:unconfined_t \
-    -v $(pwd)/config.json:/config.json \
-    -v $(pwd)/output:/output \
-    quay.io/centos-bootc/bootc-image-builder:latest \
-    --type qcow2 \
-    --config /config.json \
-    quay.io/centos-bootc/fedora-bootc:eln
-```
-
-### Using local containers
-
-To use containers from local container's storage rather than a registry, we need to ensure two things:
-- the container exists in local storage
-- mount the local container storage
-
-Since the container is run in `rootful` only root container storage paths are allowed.
-
 ```bash
 sudo podman run \
     --rm \
@@ -67,11 +44,12 @@ sudo podman run \
     quay.io/centos-bootc/bootc-image-builder:latest \
     --type qcow2 \
     --config /config.json \
-    --local \
-    localhost/bootc:eln
+    quay.io/centos-bootc/fedora-bootc:eln
 ```
 
-When using the --local flag, we need to mount the storage path as a volume. With this enabled, it is assumed that the target container is in the container storage.
+Note: we need to mount the storage path as a volume, since using containers-storage is the new default. If the target container is not
+already in the local store, `bootc-image-builder` will attempt to copy it into containers-storage. The `--remote` flag can
+be used to skip this and use the image from the remote registry.
 
 ### Running the resulting QCOW2 file on Linux (x86_64)