docs: update UI credential requirement for Quickstart (#1987)

* update UI credential requirement for Quickstart

* Update quickstart.md

Co-authored-by: Mars Lan <[email protected]>

docs/quickstart.md

@@ -8,7 +8,7 @@
     ./docker/quickstart.sh
     ```
     This step takes a while to run the first time, and it may be difficult to tell if DataHub is fully up and running from the combined log. Please use [this guide](debugging.md#how-can-i-confirm-if-all-docker-containers-are-running-as-expected-after-a-quickstart) to verify that each container is running correctly.
-5. At this point, you should be able to start DataHub by opening [http://localhost:9001](http://localhost:9001) in your browser. You can sign in using `datahub` as both username and password. However, you'll notice that no data has been ingested yet.
+5. At this point, you should be able to start DataHub by opening [http://localhost:9001](http://localhost:9001) in your browser. You can sign in using `datahub` as  username and any password (no password validation by default). However, you'll notice that no data has been ingested yet.
 6. To ingest provided [sample data](https://github.com/linkedin/datahub/blob/master/metadata-ingestion/mce-cli/bootstrap_mce.dat) to DataHub, switch to a new terminal window, `cd` into the cloned `datahub` repo, and run the following command:
     ```
     ./docker/ingestion/ingestion.sh