DOCS-15189 (#899)

* DOCS-15189 init

* add 5.3.0 changelog

* update 5.3.0 Jira Link

* removing audit log mention in 5.3

Author: ianf-mongodb

config/changelog_conf.yaml

@@ -13,6 +13,7 @@ groups:
     - Querying
     - Query Execution
     - Query Language
+    - Query Planning
     - Indexing
     - Index Maintenance
     - Geo
@@ -44,11 +45,13 @@ groups:
     - Shell
     - Usability
     - HTTP Console
+    - Client-side Field-level Encryption
   "Build and Packaging":
     - Build
     - Build/compile
     - Packaging
     - Mobile
+    - Change streams
   "Internals":
     - Testing
     - Python tests