Add AdamW to the supported optimizers (#672)

Co-authored-by: NJeff Rasley <jerasley@microsoft.com>

docs/_pages/config-json.md

@@ -34,7 +34,7 @@ title: "DeepSpeed Configuration JSON"
 
 | Fields | Value                                                        | Example                        |
 | ------ | ------------------------------------------------------------ | ------------------------------ |
-| type   | The optimizer name. DeepSpeed natively supports **Adam**, **OneBitAdam**, and **Lamb** optimizers and will import other optimizers from [torch](https://pytorch.org/docs/stable/optim.html). | `"Adam"`                         |
+| type   | The optimizer name. DeepSpeed natively supports **Adam**, **AdamW**, **OneBitAdam**, and **Lamb** optimizers and will import other optimizers from [torch](https://pytorch.org/docs/stable/optim.html). | `"Adam"`                         |
 | params | Dictionary of parameters to instantiate optimizer. The parameter names must match the optimizer constructor signature (e.g., for [Adam](https://pytorch.org/docs/stable/optim.html#torch.optim.Adam)). | `{"lr": 0.001, "eps": 1e-8}` |
 
   Example of ***optimizer*** with Adam