build: image-manifest enabled by default for cache export

Signed-off-by: CrazyMax <[email protected]>

Author: crazy-max

content/manuals/build/cache/backends/_index.md

@@ -179,3 +179,6 @@ $ docker buildx build --push -t <registry>/<image> \
   --cache-to type=registry,ref=<registry>/<cache-image>,oci-mediatypes=true,image-manifest=true \
   --cache-from type=registry,ref=<registry>/<cache-image> .
 ```
+
+> [!NOTE]
+> Since BuildKit v0.21, `image-manifest` is enabled by default.

content/manuals/build/cache/backends/local.md

@@ -25,13 +25,13 @@ The following table describes the available CSV parameters that you can pass to
 `--cache-to` and `--cache-from`.
 
 | Name                | Option       | Type                    | Default | Description                                                                                                                     |
-| ------------------- | ------------ | ----------------------- | ------- | ------------------------------------------------------------------------------------------------------------------------------- |
+|---------------------|--------------|-------------------------|---------|---------------------------------------------------------------------------------------------------------------------------------|
 | `src`               | `cache-from` | String                  |         | Path of the local directory where cache gets imported from.                                                                     |
 | `digest`            | `cache-from` | String                  |         | Digest of manifest to import, see [cache versioning][4].                                                                        |
 | `dest`              | `cache-to`   | String                  |         | Path of the local directory where cache gets exported to.                                                                       |
 | `mode`              | `cache-to`   | `min`,`max`             | `min`   | Cache layers to export, see [cache mode][1].                                                                                    |
 | `oci-mediatypes`    | `cache-to`   | `true`,`false`          | `true`  | Use OCI media types in exported manifests, see [OCI media types][2].                                                            |
-| `image-manifest`    | `cache-to`   | `true`,`false`          | `false` | When using OCI media types, generate an image manifest instead of an image index for the cache image, see [OCI media types][2]. |
+| `image-manifest`    | `cache-to`   | `true`,`false`          | `true`  | When using OCI media types, generate an image manifest instead of an image index for the cache image, see [OCI media types][2]. |
 | `compression`       | `cache-to`   | `gzip`,`estargz`,`zstd` | `gzip`  | Compression type, see [cache compression][3].                                                                                   |
 | `compression-level` | `cache-to`   | `0..22`                 |         | Compression level, see [cache compression][3].                                                                                  |
 | `force-compression` | `cache-to`   | `true`,`false`          | `false` | Forcibly apply compression, see [cache compression][3].                                                                         |

content/manuals/build/cache/backends/registry.md

@@ -37,11 +37,11 @@ The following table describes the available CSV parameters that you can pass to
 `--cache-to` and `--cache-from`.
 
 | Name                | Option                  | Type                    | Default | Description                                                                                                                     |
-| ------------------- | ----------------------- | ----------------------- | ------- | ------------------------------------------------------------------------------------------------------------------------------- |
+|---------------------|-------------------------|-------------------------|---------|---------------------------------------------------------------------------------------------------------------------------------|
 | `ref`               | `cache-to`,`cache-from` | String                  |         | Full name of the cache image to import.                                                                                         |
 | `mode`              | `cache-to`              | `min`,`max`             | `min`   | Cache layers to export, see [cache mode][1].                                                                                    |
 | `oci-mediatypes`    | `cache-to`              | `true`,`false`          | `true`  | Use OCI media types in exported manifests, see [OCI media types][2].                                                            |
-| `image-manifest`    | `cache-to`              | `true`,`false`          | `false` | When using OCI media types, generate an image manifest instead of an image index for the cache image, see [OCI media types][2]. |
+| `image-manifest`    | `cache-to`              | `true`,`false`          | `true`  | When using OCI media types, generate an image manifest instead of an image index for the cache image, see [OCI media types][2]. |
 | `compression`       | `cache-to`              | `gzip`,`estargz`,`zstd` | `gzip`  | Compression type, see [cache compression][3].                                                                                   |
 | `compression-level` | `cache-to`              | `0..22`                 |         | Compression level, see [cache compression][3].                                                                                  |
 | `force-compression` | `cache-to`              | `true`,`false`          | `false` | Forcibly apply compression, see [cache compression][3].                                                                         |