chore: added cockroachdb to Polis byod section (#2190)

added cockroachdb

Author: deepakprabhakara

docs/polis/deploy/env-variables.mdx

@@ -223,7 +223,7 @@ NPM library option: `db.engine`
 
 ### **DB_TYPE**
 
-Only needed when DB_ENGINE is sql. Supported values are `postgres`, `mysql`, `mariadb`, `mssql`
+Only needed when DB_ENGINE is sql. Supported values are `postgres`, `cockroachdb`, `mysql`, `mariadb`, `mssql`
 
 Default: `postgres`