docs: deprecate empty Config fields in image inspect API

Image config fields like Cmd, Entrypoint, Env, etc. will be omitted from
/images/{name}/json response when empty, starting in v29.0.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

Author: vvoland

docs/deprecated.md

@@ -53,6 +53,7 @@ The following table provides an overview of the current status of deprecated fea
 
 | Status     | Feature                                                                                                                            | Deprecated | Remove |
 |------------|------------------------------------------------------------------------------------------------------------------------------------|------------|--------|
+| Deprecated | [Empty/nil fields in image Config from inspect API](#emptynil-fields-in-image-config-from-inspect-api)                             | v28.3      | v29.0  |
 | Deprecated | [Configuration for pushing  non-distributable artifacts](#configuration-for-pushing-non-distributable-artifacts)                   | v28.0      | v29.0  |
 | Deprecated | [`--time` option on `docker stop` and `docker restart`](#--time-option-on-docker-stop-and-docker-restart)                          | v28.0      | -      |
 | Removed    | [Non-standard fields in image inspect](#non-standard-fields-in-image-inspect)                                                      | v27.0      | v28.2  |
@@ -161,14 +162,41 @@ entirely.
 
 ### `--time` option on `docker stop` and `docker restart`
 
-**Deprecated in Release: v28.0**
+**Deprecated in Release: v28.3**
 
 The `--time` option for the `docker stop`, `docker container stop`, `docker restart`,
 and `docker container restart` commands has been renamed to `--timeout` for
 consistency with other uses of timeout options. The `--time` option is now
 deprecated and hidden, but remains functional for backward compatibility.
 Users are encouraged to migrate to using the `--timeout` option instead.
 
+### Empty/nil fields in image Config from inspect API
+
+**Deprecated in Release: v28.0**
+**Target For Removal In Release: v29.0**
+
+The `Config` field returned by `docker image inspect` (and the `GET /images/{name}/json` 
+API endpoint) currently includes certain fields even when they are empty or nil. 
+Starting in Docker v29.0, the following fields will be omitted from the API response 
+when they contain empty or default values:
+
+- `Cmd`
+- `Entrypoint`
+- `Env`
+- `Labels`
+- `OnBuild`
+- `User`
+- `Volumes`
+- `WorkingDir`
+
+Applications consuming the image inspect API should be updated to handle the
+absence of these fields gracefully, treating missing fields as having their
+default/empty values.
+
+For API version corresponding to Docker v29.0, these fields will be omitted when
+empty. They will continue to be included when using clients that request an older
+API version for backward compatibility.
+
 ### Non-standard fields in image inspect
 
 **Deprecated in Release: v27.0**