ENG-1404: Hide region CLI flag for cluster creation (#15277)

Hide region CLI flag

Author: nmiculinic

src/lightning_app/CHANGELOG.md

@@ -32,6 +32,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 - Fixed an issue when using the CLI without arguments ([#14877](https://github.com/Lightning-AI/lightning/pull/14877))
 - Fixed a bug where the upload files endpoint would raise an error when running locally ([#14924](https://github.com/Lightning-AI/lightning/pull/14924))
+- Fixed BYOC cluster region selector -> hiding it from help since only us-east-1 has been tested and is recommended ([#15277]https://github.com/Lightning-AI/lightning/pull/15277)
 - Fixed a bug when launching an app on multiple clusters ([#15226](https://github.com/Lightning-AI/lightning/pull/15226))
 
 ## [0.6.2] - 2022-09-21

src/lightning_app/cli/lightning_cli_create.py

@@ -25,6 +25,7 @@ def create() -> None:
     required=False,
     default="us-east-1",
     help="AWS region that is used to host the associated resources.",
+    hidden=True,
 )
 @click.option(
     "--instance-types",