Update README.md

Author: tylertreat

README.md

@@ -7,3 +7,28 @@ API](https://cloud.google.com/dataprep/docs/html/API-Overview_145281442).
 For triggering Dataprep flows using Dataflow templates directly rather than
 the Dataprep API, see
 [gcp-dataflow-gcf-trigger](https://github.com/RealKinetic/gcp-dataflow-gcf-trigger).
+
+## Deploying
+
+Run the following command to deploy this Cloud Function:
+
+```
+$ gcloud functions deploy <function-name> \
+    --entry-point trigger \
+    --trigger-bucket gs://<my-bucket> \
+    --set-env-vars RECIPE_ID=<dataprep-recipe>,DATAPREP_TOKEN=<dataprep-token> \
+    --runtime python37
+```
+
+Ensure that the trigger bucket matches the bucket used for the Dataprep
+recipe.
+
+## Environment Variables
+
+As shown above, this Cloud Function requires two environment variables:
+
+- `RECIPE_ID`: the ID of the Dataprep recipe to start jobs for. The provided
+recipe must have a parameterized dataset with a variable called `file` which
+is the file to process from the configured bucket.
+- `DATAPREP_TOKEN`: [Dataprep access token](https://cloud.google.com/dataprep/docs/html/Access-Tokens-Page_145281436)
+used to authenticate with the Dataprep API