tune model serving framework: add field details for model configs (#1976)

* tune model serving framework: add field details for model configs

Signed-off-by: Yaliang Wu <ylwu@amazon.com>

* Update _ml-commons-plugin/model-serving-framework.md

Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>

* Update _ml-commons-plugin/model-serving-framework.md

* Update _ml-commons-plugin/model-serving-framework.md

Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>

* Update _ml-commons-plugin/model-serving-framework.md

Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>

* Update _ml-commons-plugin/model-serving-framework.md

Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>

* Update _ml-commons-plugin/model-serving-framework.md

Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>

* Update _ml-commons-plugin/model-serving-framework.md

Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>

* Update _ml-commons-plugin/model-serving-framework.md

Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>

* Update _ml-commons-plugin/model-serving-framework.md

Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>

Signed-off-by: Yaliang Wu <ylwu@amazon.com>
Co-authored-by: Naarcha-AWS <97990722+Naarcha-AWS@users.noreply.github.com>
Co-authored-by: kolchfa-aws <105444904+kolchfa-aws@users.noreply.github.com>

_ml-commons-plugin/model-serving-framework.md

@@ -48,9 +48,18 @@ Field | Data Type | Description
 `name`| string | The name of the model. |
 `version` | string | The version number of the model. Since OpenSearch does not enforce a specific version schema for models, you can choose any number or format that makes sense for your models. |
 `model_format` | string | The portable format of the model file. Currently only supports `TORCH_SCRIPT`. |
-`model_config` | string | The model's configuration, including the `model_type`, `embedding_dimension`, and `framework_type`. |
+[`model_config`](#the-model_config-object) | json object | The model's configuration, including the `model_type`, `embedding_dimension`, and `framework_type`. |
 `url` | string | The URL where the model is located. |
 
+### The `model_config` object
+
+| Field | Data Type | Description |
+| :--- | :--- | :--- |
+| `model_type` | string | The model type, such as `bert`. For a Huggingface model, the model type is specified in `config.json`. For an example, see the [`all-MiniLM-L6-v2` Huggingface model `config.json`](https://huggingface.co/sentence-transformers/all-MiniLM-L6-v2/blob/main/config.json#L15).|
+| `embedding_dimension` | integer | The dimension of the model-generated dense vector. For a Huggingface model, the dimension is specified in the model card. For example, in the [`all-MiniLM-L6-v2` Huggingface model card](https://huggingface.co/sentence-transformers/all-MiniLM-L6-v2), the statement `384 dimensional dense vector space` specifies 384 as the embedding dimension. |
+| `framework_type` | string  | The framework the model is using. Currently, we support `sentence_transformers` and `huggingface_transformers` frameworks. The `sentence_transformers` model outputs text embeddings directly, so ML Commons does not perform any post processing. For `huggingface_transformers`, ML Commons performs post processing by applying mean pooling to get text embeddings. See the example [`all-MiniLM-L6-v2` Huggingface model](https://huggingface.co/sentence-transformers/all-MiniLM-L6-v2) for more details. |
+| `all_config` _(Optional)_ | string | This field is used for reference purposes. You can specify all model configurations in this field. For example, if you are using a Huggingface model, you can minify the `config.json` file to one line and save its contents in the `all_config` field. Once the model is uploaded, you can use the get model API operation to get all model configurations stored in this field. |
+
 #### Sample request