update example env to use better-sqlite3 and add DB_FILENAME

.example.env

@@ -11,9 +11,17 @@ DEFAULT_DOMAIN=localhost:3000
 JWT_SECRET=
 
 # Optional - Database client. Available clients for the supported databases:
-# pg | pg-native | sqlite3 | better-sqlite3 | mysql | mysql2 | oracledb | tedious
-DB_CLIENT=sqlite3
-# SQL database credential details, only if you use Postgres or MySQL
+# pg | better-sqlite3 | mysql2
+# other supported drivers that you can use but you have to manually install them with npm:
+# pg-native | sqlite3 | mysql
+DB_CLIENT=better-sqlite3
+
+# Optional - SQLite database file path
+# Only if you're using SQLite
+DB_FILENAME=db/data
+
+# Optional - SQL database credential details
+# Only if you're using Postgres or MySQL
 DB_HOST=localhost
 DB_PORT=5432
 DB_NAME=kutt