HARMONY-1938: Document updates to EDL client app environment variables.

ENV_CHANGELOG.md

@@ -2,6 +2,14 @@
 Any changes to the environment variables will be documented in this file in chronological
 order with the most recent changes first.
 
+# 2024-12-03
+### Added
+- USE_EDL_CLIENT_APP - whether to use an EDL client application to enable admin and deployment endpoints and allow OAuth workflows.
+- EDL_TOKEN - required if USE_EDL_CLIENT_APP is set to false. An EDL token to use for all requests to the CMR and to download data in backend services.
+
+### Changed
+OAUTH_CLIENT_ID, OAUTH_UID, OAUTH_PASSWORD, and OAUTH_REDIRECT_URI are no longer required if USE_EDL_CLIENT_APP is false.
+
 # 2024-11-05
 ### Added
 - LABEL_FILTER_COMPLETION_COUNT - the max number of labels to retrieve to populate label filter auto-complete