[wic] README.md: update env usage

[Trevor Woerner <twoerner@gmail.com>]

Update the README to clarify that the --vars argument works with either
one BitBake-generated environment file, or by pointing it at a directory
of environment files.

Signed-off-by: Trevor Woerner <twoerner@gmail.com>
---
 README.md | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index 8ee02d89738b..c6fed6626e10 100644
--- a/README.md
+++ b/README.md
@@ -1,13 +1,13 @@
 # WIC Standalone
 
 This packages the OpenEmbedded Image Creator (`wic`) as an installable
-Python CLI using Hatch. It either consumes BitBake-exported environment
-files (generated via `bitbake -c rootfs_wicenv <image>`) or will invoke
-BitBake directly (if available on the PATH).
+Python CLI using Hatch. It either consumes a BitBake-exported
+environment file or folder (generated via `bitbake -c rootfs_wicenv
+<image>`) or will invoke BitBake directly (if available on the PATH).
 
 ## Quick start
 
-### Using wicenv
+### Using wicenv (one environment file)
 1. Ensure you have a BitBake-generated `<image>.env` file (from `rootfs_wicenv`).
 2. Install locally for development:
    ```bash
@@ -18,6 +18,17 @@ BitBake directly (if available on the PATH).
    hatch run wic --vars /path/to/<image>.env --help
    ```
 
+### Using wicenv (environment folder)
+1. Ensure you have a folder with BitBake-generated `<image>.env` files (from `rootfs_wicenv`).
+2. Install locally for development:
+   ```bash
+   hatch shell
+   ```
+3. Run the CLI:
+   ```bash
+   hatch run wic --vars /path/to/envfiledir --help
+   ```
+
 ### With bitbake
 1. Ensure you have bitbake available in your PATH.
 2. Install locally for development:
-- 
2.51.0