[Doc] Clarify that graviton option of databricks_node_type could be used on Azure (#4125)

## Changes
<!-- Summary of your changes that are easy to understand -->

When used on Azure the `databricks_node_type` will search for VMs built
on Azure Cobalt CPUs.

## Tests
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other relevant tests
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- [ ] `make test` run locally
- [x] relevant change in `docs/` folder
- [ ] covered with integration tests in `internal/acceptance`
- [ ] relevant acceptance tests are passing
- [ ] using Go SDK

Author: alexott

docs/data-sources/node_type.md

@@ -56,7 +56,7 @@ Data source allows you to pick groups by the following attributes
   * `GPU Accelerated` (AWS, Azure)
 * `photon_worker_capable` - (Optional) Pick only nodes that can run Photon workers. Defaults to _false_.
 * `photon_driver_capable` - (Optional) Pick only nodes that can run Photon driver. Defaults to _false_.
-* `graviton` - (boolean, optional)  if we should limit the search only to nodes with AWS Graviton CPUs. Default to _false_.
+* `graviton` - (boolean, optional)  if we should limit the search only to nodes with AWS Graviton or Azure Cobalt CPUs. Default to _false_.
 * `fleet` - (boolean, optional)  if we should limit the search only to [AWS fleet instance types](https://docs.databricks.com/compute/aws-fleet-instances.html). Default to _false_.
 * `is_io_cache_enabled` - (Optional) . Pick only nodes that have IO Cache. Defaults to _false_.
 * `support_port_forwarding` - (Optional) Pick only nodes that support port forwarding. Defaults to _false_.