docs: Add docs for basic auth to airflow stable rest api (#876)

* docs: Add docs for basic auth to airflow stable rest api

* Add console instructions for pod exec

airflow/plural/docs/basic-auth.md

@@ -0,0 +1,104 @@
+## Using the Airflow API
+
+To use the [Airflow Stable REST API](https://airflow.apache.org/docs/apache-airflow/stable/stable-rest-api-ref.html) 
+follow the steps below
+
+### edit values.yaml
+
+You'll need edit `airflow/helm/airflow/values.yaml` in your installation repo to enable basic auth to the REST API:
+
+```yaml
+airflow:
+  airflow:
+    airflow:
+      config:
+        AIRFLOW__API__AUTH_BACKENDS: airflow.api.auth.backend.basic_auth
+```
+
+Alternatively, you should be able to do this in the configuration section for airflow in your plural console as well.
+
+### exec into airflow scheduler pod
+
+In order to create an Airflow user that will be used to authenticate to the API, you will need to run Airflow CLI 
+commands. This requires an exec into your Airflow environment. There are two ways you could do this (via local CLI or 
+via Plural Console). Choose whichever works best for you:
+
+**__via local CLI__**
+
+1. Identify the scheduler pod by running `kubectl get pods -n airflow`
+2. Exec into the scheduler pod by running `kubectl exec -ti airflow-scheduler-nnn-nnn --namespace airflow -- /bin/bash`
+
+**__via Plural Console__**
+
+1. Click on the `Pods` icon on the left-hand nav bar
+2. Filter the pods down to the `Airflow` namespace
+3. Click on a pod running an Airflow Scheduler
+4. On the container line-item called `airflow-scheduler` click the shell icon to launch a shell where you can run Airflow 
+CLI commands
+
+### create an airflow user
+
+Now that you have a shell to the scheduler container, you can run an Airflow command to create a user (see Airflow Docs 
+[here](https://airflow.apache.org/docs/apache-airflow/stable/security/webserver.html#web-authentication)):
+
+```shell
+(airflow) airflow users create -e [email protected] -f Peter -l Parker -p my_super_secret_password -r Admin -u pparker
+```
+
+```shell
+airflow@airflow-scheduler-nnn-nnn:/opt/airflow$ airflow users create -e [email protected] -f Peter -l Parker -p my_super_secret_password -r Admin -u pparker
+```
+
+### customize role (optional)
+
+If you want to customize the Role for your API user and which permissions it has, you can do so in the Airflow UI. See 
+more details [here](https://airflow.apache.org/docs/apache-airflow/stable/security/access-control.html)
+
+## Making API Calls
+
+Once you've completed the steps above to configure basic auth, you should be able to make api requests to your Airflow 
+instance accordingly:
+
+```python
+    # trigger a DAG in Python 
+
+    import json
+    import requests
+    from requests.auth import HTTPBasicAuth
+    
+    # Define your base URL and dag ID as variables
+    base_url = "<replace with your base_url>" # Your base URL (can be found in your project's context.yaml - spec.configuration.airflow.hostname)
+    dag_id = "<replace with dag_id you want to trigger>"
+    
+    # Define your username and password
+    username="pparker"
+    password="my_super_secret_password"
+    
+    # Construct and execute http request - (this one triggers a dag)
+    response = requests.post(
+        url=f"https://{base_url}/api/v1/dags/{dag_id}/dagRuns",
+        headers={"accept": "application/json", "content-type": "application/json"},
+        data=json.dumps({}),
+        auth=HTTPBasicAuth(username=username, password=password)
+    )
+    print(response.json())
+```
+
+```bash
+    # Define your base URL and dag ID as variables
+    base_url="<replace with your base_url>" # Your base URL (can be found in your project's context.yaml - spec.configuration.airflow.hostname)
+    dag_id="<replace with dag_id you want to trigger>"
+    
+    # Define your username and password
+    username="pparker"
+    password="my_super_secret_password"
+    
+    # Construct and execute the curl command - (this one triggers a dag)
+    curl -X POST "$base_url/api/v1/dags/$dag_id/dagRuns" \
+    -H "accept: application/json" \
+    -H "content-type: application/json" \
+    -d "{}" \
+    -u "$username:$password"
+```
+
+For complete documentation on the API Stable REST API, be sure to visit the OSS docs [here](https://airflow.apache.org/docs/apache-airflow/stable/stable-rest-api-ref.html).