chore: Adding/categorizing missing flags in `FEATURE_FLAGS.md` (#21474)

Co-authored-by: Geido <60598000+geido@users.noreply.github.com>

RESOURCES/FEATURE_FLAGS.md

@@ -33,6 +33,8 @@ These features are considered **unfinished** and should only be used on developm
 - SHARE_QUERIES_VIA_KV_STORE
 - TAGGING_SYSTEM
 - ENABLE_TEMPLATE_REMOVE_FILTERS
+- DRILL_TO_DETAIL
+- ENABLE_ADVANCED_DATA_TYPES
 
 ## In Testing
 These features are **finished** but currently being tested. They are usable, but may still contain some bugs.
@@ -44,6 +46,15 @@ These features are **finished** but currently being tested. They are usable, but
 - VERSIONED_EXPORT
 - ENABLE_JAVASCRIPT_CONTROLS
 - GENERIC_CHART_AXES
+- ENABLE_FILTER_BOX_MIGRATION
+- UX_BETA
+- USE_ANALAGOUS_COLORS
+- DASHBOARD_EDIT_CHART_IN_NEW_TAB
+- CACHE_IMPERSONATION
+- RLS_IN_SQLLAB
+- DASHBOARD_FILTERS_EXPERIMENTAL
+- ALLOW_FULL_CSV_EXPORT
+
 
 ## Stable
 These features flags are **safe for production** and have been tested.
@@ -57,9 +68,19 @@ These features flags are **safe for production** and have been tested.
 - SQL_VALIDATORS_BY_ENGINE [(docs)](https://superset.apache.org/docs/installation/sql-templating)
 - SQLLAB_BACKEND_PERSISTENCE
 - THUMBNAILS [(docs)](https://superset.apache.org/docs/installation/cache)
+- ENABLE_EXPLORE_DRAG_AND_DROP
+- ENABLE_DND_WITH_CLICK_UX
+- EMBEDDABLE_CHARTS
+- EMBEDDED_SUPERSET
+- ALERTS_ATTACH_REPORTS
+- ALLOW_ADHOC_SUBQUERY
+- DRUID_JOINS
+- DISABLE_LEGACY_DATASOURCE_EDITOR
+- ENFORCE_DB_ENCRYPTION_UI
 
 ## Deprecated Flags
 These features flags currently default to True and **will be removed in a future major release**. For this current release you can turn them off by setting your config to False, but it is advised to remove or set these flags in your local configuration to **True** so that you do not experience any unexpected changes in a future release.
 
 - ALLOW_DASHBOARD_DOMAIN_SHARDING
 - DISPLAY_MARKDOWN_HTML
+- FORCE_DATABASE_CONNECTIONS_SSL