chore: update readme for alibaba resource detector (#2056)

Update README of Alibaba resource detector to add a table with values getting detected.

Part Of #2055

Signed-off-by: maryliag <marylia.gutierrez@grafana.com>

detectors/node/opentelemetry-resource-detector-alibaba-cloud/README.md

@@ -28,6 +28,19 @@ const tracerProvider = new NodeTracerProvider({ resource });
 
 ## Available detectors
 
-- `alibabaCloudEcsDetector`: Populates `cloud` and `host` for processes running on [Alibaba Cloud ECS](https://www.alibabacloud.com/product/ecs).
+### Alibaba Cloud Ecs Detector
+
+Populates `cloud` and `host` for processes running on [Alibaba Cloud ECS](https://www.alibabacloud.com/product/ecs). More info about Alibaba Instance Identities can be found [here](https://www.alibabacloud.com/help/en/ecs/user-guide/use-instance-identities).
+
+| Resource Attribute      |  Description                                                    |
+|-------------------------|-----------------------------------------------------------------|
+| cloud.account.id        | Value of `owner-account-id` on Alibaba Cloud                    |
+| cloud.availability_zone | Value of `zone-id` on Alibaba Cloud                             |
+| cloud.platform          | In this context, it's always `alibaba_cloud_ecs`                |
+| cloud.provider          | In this context, it's always `alibaba_cloud`                    |
+| cloud.region            | Value of `region-id` on Alibaba Cloud                           |
+| host.id                 | Value of `instance-id` on Alibaba Cloud                         |
+| host.name               | The hostname for the app, retrieve from the `hostname` endpoint |
+| host.type               | Value of `instance-type` on Alibaba Cloud                       |
 
 [resource-semantic_conventions]: https://github.com/open-telemetry/opentelemetry-specification/tree/master/specification/resource/semantic_conventions