docs(ingest): Add instructions to install required dependency (#2995)

metadata-ingestion/README.md

@@ -979,8 +979,11 @@ If you're simply looking to run ingestion on a schedule, take a look at these sa
 The Airflow lineage backend is only supported in Airflow 1.10.15+ and 2.0.2+.
 
 :::
-
-1. First, you must configure an Airflow hook for Datahub. We support both a Datahub REST hook and a Kafka-based hook, but you only need one.
+1. You need to install the required dependency in your airflow. See https://registry.astronomer.io/providers/datahub/modules/datahublineagebackend
+  ```shell
+    pip install acryl-datahub[airflow]
+  ```
+2. You must configure an Airflow hook for Datahub. We support both a Datahub REST hook and a Kafka-based hook, but you only need one.
 
    ```shell
    # For REST-based:
@@ -989,7 +992,7 @@ The Airflow lineage backend is only supported in Airflow 1.10.15+ and 2.0.2+.
    airflow connections add  --conn-type 'datahub_kafka' 'datahub_kafka_default' --conn-host 'broker:9092' --conn-extra '{}'
    ```
 
-2. Add the following lines to your `airflow.cfg` file.
+3. Add the following lines to your `airflow.cfg` file.
    ```ini
    [lineage]
    backend = datahub_provider.lineage.datahub.DatahubLineageBackend
@@ -1005,8 +1008,8 @@ The Airflow lineage backend is only supported in Airflow 1.10.15+ and 2.0.2+.
    - `capture_ownership_info` (defaults to true): If true, the owners field of the DAG will be capture as a DataHub corpuser.
    - `capture_tags_info` (defaults to true): If true, the tags field of the DAG will be captured as DataHub tags.
    - `graceful_exceptions` (defaults to true): If set to true, most runtime errors in the lineage backend will be suppressed and will not cause the overall task to fail. Note that configuration issues will still throw exceptions.
-3. Configure `inlets` and `outlets` for your Airflow operators. For reference, look at the sample DAG in [`lineage_backend_demo.py`](./src/datahub_provider/example_dags/lineage_backend_demo.py), or reference [`lineage_backend_taskflow_demo.py`](./src/datahub_provider/example_dags/lineage_backend_taskflow_demo.py) if you're using the [TaskFlow API](https://airflow.apache.org/docs/apache-airflow/stable/concepts/taskflow.html).
-4. [optional] Learn more about [Airflow lineage](https://airflow.apache.org/docs/apache-airflow/stable/lineage.html), including shorthand notation and some automation.
+4. Configure `inlets` and `outlets` for your Airflow operators. For reference, look at the sample DAG in [`lineage_backend_demo.py`](./src/datahub_provider/example_dags/lineage_backend_demo.py), or reference [`lineage_backend_taskflow_demo.py`](./src/datahub_provider/example_dags/lineage_backend_taskflow_demo.py) if you're using the [TaskFlow API](https://airflow.apache.org/docs/apache-airflow/stable/concepts/taskflow.html).
+5. [optional] Learn more about [Airflow lineage](https://airflow.apache.org/docs/apache-airflow/stable/lineage.html), including shorthand notation and some automation.
 
 ### Emitting lineage via a separate operator