define media type for oci-layout

To add a new specific media type for oci-layout, serving over its
transportation.

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

Author: xiekeyang

image-layout.md

@@ -129,6 +129,7 @@ $ cat ./blobs/sha256/e692418e4cbaf90ca69d05a66403747baa33ee08806650b51fab815ad7f
 
 This JSON object serves as a marker for the base of an Open Container Image Layout and to provide the version of the image-layout in use.
 The `imageLayoutVersion` value will align with the OCI Image Specification version at the time changes to the layout are made, and will pin a given version until changes to the image layout are required.
+This section defines the `application/vnd.oci.layout.header.v1+json` [media type](media-types.md).
 
 ### oci-layout Example
 

media-types.md

@@ -3,6 +3,7 @@
 The following media types identify the formats described here and their referenced resources:
 
 - `application/vnd.oci.descriptor.v1+json`: [Content Descriptor](descriptor.md)
+- `application/vnd.oci.layout.header.v1+json`: [OCI Layout](image-layout.md#oci-layout-file)
 - `application/vnd.oci.image.index.v1+json`: [Image Index](image-index.md)
 - `application/vnd.oci.image.manifest.v1+json`: [Image manifest](manifest.md#image-manifest)
 - `application/vnd.oci.image.config.v1+json`: [Image config](config.md)