Rename file and update README.md (#44)

Author: mfvanek

README.md

@@ -40,6 +40,7 @@ For more information please see [PostgreSQL Versioning Policy](https://www.postg
 16. Indexes [with boolean](https://habr.com/ru/companies/tensor/articles/488104/) ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/indexes_with_boolean.sql)).
 17. Tables with [not valid constraints](https://habr.com/ru/articles/800121/) ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/check_not_valid_constraints.sql)).
 18. B-tree indexes [on array columns](https://habr.com/ru/articles/800121/) ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/btree_indexes_on_array_columns.sql)).
+19. [Sequence overflow](https://habr.com/ru/articles/800121/) ([sql](https://github.com/mfvanek/pg-index-health-sql/blob/master/sql/sequence_overflow.sql)).
 
 ## Local development