Document new feature in the change log
@@ -5,6 +5,7 @@ We also use this change log to document new features that maintain backward comp
## New features since last version update
+- 6 October 2021: Add three configuration parameters to control the metadata sanitizer step of the workflow. These parameters allow users to specify the metadata columns to use for strain names (`metadata_id_columns`) and to resolve duplicate records with database ids (`database_id_columns`). The new `error_on_duplicate_strains` parameter allows users to ask the workflow to exit with an error when any duplicates appear in the metadata. [See the configuration reference for more details](https://docs.nextstrain.org/projects/ncov/en/latest/reference/configuration.html#sanitize-metadata). ([#728](https://github.com/nextstrain/ncov/pull/728))
- 6 October 2021: Update clades with `21I (Delta)` and `21J (Delta)` viruses. These are subclades within `21A (Delta)`. Based on mutations they should have largely Delta-like phenotypes, although additional ORF1a mutations in `21J (Delta)` appear to confer higher fitness.
## v9 (6 October 2021)
