simplify decision tree for artifacts

Signed-off-by: Sajay Antony <sajaya@microsoft.com>

docs/concepts/artifact.mdx

@@ -64,8 +64,8 @@ flowchart TD
     B -->|No| E[type=manifest.config.mediaType]
 ```
 
-For aritifact authors, the the choice of whether to set the `artifactType` or
-`config.mediaType` depends on the contents and shape of the artifact and is discussed in the following sections.
+For aritifact authors, the sections below should help deciding on the blob and 
+config mediaTypes.
 
 ## Dissecting the Manifest
 
@@ -110,10 +110,36 @@ in this case the config is an empty blob as per the [empty descriptor guidance][
 
 ### Artifacts with config
 
-Clients can use `config.mediaType` property  to
-declare the artifact type. The `config.mediaType` may be used when artifacts have a valid config blob and
-the mediaType matches the config blob and type of the artifact. For example the
-artifact type below for the helm chart is `application/vnd.cncf.helm.config.v1+json`
+Clients have been using the `config.mediaType` property  to declare the artifact type. 
+For OCI artifacts that have a valid config blob the config blob may use its own 
+mediaType and the `artifactType` property can be set to indicate the type of artifact. 
+
+```json
+   {
+     "schemaVersion": 2,
+     "mediaType": "application/vnd.oci.image.manifest.v1+json",
+     "artifactType": "application/vnd.example+type",
+     "config": {
+       "mediaType": "application/vnd.example.config.v1+json",
+       "digest": "sha256:5891b5b522d5df086d0ff0b110fbd9d21bb4fc7163af34d08286a2e846f6be03",
+       "size": 123
+     },
+     "layers": [
+       {
+         "mediaType": "application/vnd.example.data.v1.tar+gzip",
+         "digest": "sha256:e258d248fda94c63753607f7c4494ee0fcbe92f1a76bfdac795c9d84101eb317",
+         "size": 1234
+       }
+     ]
+   }
+```
+
+#### Prior Art
+
+Before version 1.1 of the [image specification][image-spec], the `config.mediaType` 
+was used to indicate the type of the artifact. 
+For example the artifact type below for the helm chart is `application/vnd.cncf.helm.config.v1+json`
+as the manifest does not have the `artifactType` property.
 
 ```json
 {
@@ -136,10 +162,10 @@ artifact type below for the helm chart is `application/vnd.cncf.helm.config.v1+j
 
 ### Annotations only artifacts
 
-Artifacts may store metadata in the manifest as annotations and do not have a config or blobs.
+Artifacts may store metadata in the manifest as annotations and need not have a config or blobs.
 For these the `artifactType` property is used to declare the type of the artifact.
-The config property is required in the manifest for maximum compatiblity an empty layer is also created.
-as per the  [empty descriptors guidance][empty-descriptor].  
+The config property is required in the manifest and for maximum compatiblity 
+an empty layer is also created as per the  [empty descriptors guidance][empty-descriptor].  
 
 ```json
 {
@@ -167,26 +193,22 @@ as per the  [empty descriptors guidance][empty-descriptor].
 
 ### Deciding on artifactType or config.mediaType
 
-Considering the above types of artifacts, the decision tree below should help
-determine what fields to set when creating an artifact.
+Putting it all together with the types of artifacts listed above, the decision tree 
+below should help determine what fields to set when creating an artifact.
 
 ```mermaid
 graph TD
     HasBlob{Artifact has at least<br>one file or blob?}
     HasConfigData{Artifact has additional<br> metadata config blob?}
-    HasConfigEqArtifactType{Artifact has an artifactType<br>equal to the <br>the config blob mediaType?}
     
-    Artifact_NoBlobs[Specify artifactType,<br>set config and layers<br>to empty descriptors.]
-    Artifact_NoConfig[Specify artifactType, include<br>artifact in layers, set<br>config to empty descriptor.]
-    Artifact_WithConfigBlob[Specify artifactType to value,<br> specify config blob and mediaType,<br> include artifact in layers.]
-    Artifact_NoArtifactType[Specify config blob and it's mediaType<br>to indicate artifactType,<br>include artifact in layers,<br>do not set artifactType.]
+    Artifact_NoBlobs[Specify <b>artifactType</b>,<br>set config and layers<br>to empty descriptors.]
+    Artifact_NoConfig[Specify  <b>artifactType</b>, include<br>artifact in layers, set<br>config to empty descriptor.]
+    Artifact_WithConfig[Specify  <b>artifactType</b>,<br> specify config blob and mediaType,<br> include artifact in layers.]
 
     HasBlob -- No --> Artifact_NoBlobs
     HasBlob -- Yes --> HasConfigData
+    HasConfigData -- Yes --> Artifact_WithConfig
     HasConfigData -- No --> Artifact_NoConfig
-    HasConfigData -- Yes --> HasConfigEqArtifactType
-    HasConfigEqArtifactType -- Yes --> Artifact_NoArtifactType
-    HasConfigEqArtifactType -- No --> Artifact_WithConfigBlob
 ```
 
 ### Harnessing Image Indexes
@@ -231,6 +253,7 @@ specifications.
 [cas]: https://en.wikipedia.org/wiki/Content-addressable_storage
 [oci-layout]: https://github.com/opencontainers/image-spec/blob/v1.1.0-rc4/image-layout.md
 [descriptor]: https://github.com/opencontainers/image-spec/blob/v1.1.0-rc4/descriptor.md
+[image-spec]: https://github.com/opencontainers/image-spec/blob/v1.1.0-rc4/spec.md
 [image-manifest]: https://github.com/opencontainers/image-spec/blob/v1.1.0-rc4/manifest.md#image-manifest
 [image-properties]: https://github.com/opencontainers/image-spec/blob/v1.1.0-rc4/manifest.md#image-manifest-property-descriptions
 [empty-descriptor]: https://github.com/opencontainers/image-spec/blob/v1.1.0-rc4/manifest.md#guidance-for-an-empty-descriptor