add initial status documentation

Author: CarsonDavis

sde_collections/models/README_REINDEXING_STATUSES.md

@@ -0,0 +1,55 @@
+# Reindexing Status Documentation
+
+### Reindexing Not Needed
+- Variable name: `REINDEXING_NOT_NEEDED` (1)
+- Default status for new collections
+- Applied to collections in early workflow stages (research, engineering, etc.)
+
+### Reindexing Needed on LRM Dev
+- Variable name: `REINDEXING_NEEDED_ON_DEV` (2)
+- Indicates collections that need to be reindexed on LRM Dev environment
+- For collections that have already been indexed on production
+
+### Reindexing Finished on LRM Dev
+- Variable name: `REINDEXING_FINISHED_ON_DEV` (3)
+- For collections that have completed reindexing on LRM Dev
+- Currently managed manually by LRM team via admin interface
+
+### Ready for Curation
+- Variable name: `REINDEXING_READY_FOR_CURATION` (4)
+- Automatically set when:
+  - A collection's dump URLs are migrated to delta URLs AND there are curated URLs present
+  - Triggered by Collection.migrate_dump_to_delta() method
+
+### Curated
+- Variable name: `REINDEXING_CURATED` (5)
+- Automatically set when:
+  - Delta URLs are promoted to curated URLs AND there are curated URLs present
+  - Triggered by Collection.promote_to_curated() method
+
+### Indexed on Prod
+- Variable name: `REINDEXING_INDEXED_ON_PROD` (6)
+- Currently managed manually via command line
+- Future: Will be set automatically via plugin ping
+
+### Key Code Locations for Automatic Changes
+
+1. In migrate_dump_to_delta():
+```python
+# After migrating, check if we should update reindexing status
+curated_urls_count = self.curated_urls.count()
+if curated_urls_count > 0:
+    self.reindexing_status = ReindexingStatusChoices.REINDEXING_READY_FOR_CURATION
+    self.save()
+```
+
+2. In promote_to_curated():
+```python
+# After promoting, check if we should update reindexing status
+curated_urls_count = self.curated_urls.count()
+if curated_urls_count > 0:
+    self.reindexing_status = ReindexingStatusChoices.REINDEXING_CURATED
+    self.save()
+```
+
+Note: All status changes are logged in the ReindexingHistory model for tracking purposes.