Cannot run example application

[nicoabie]

Describe the bug
Instructions are outdated in packages/example/README.md and CONTRIBUTING.md

Expected behavior

Test case

If applicable, it would really help if you can add an end-to-end test-case to the packages/example project.

The package allows you to do the following:

• Modify the database schema at packages/example/sql/schema.sql.
• Define your SQL query as a .ts or .sql anywhere in the packages/example/src directory.
• Run your SQL as a Jest test case in packages/example/src/index.test.ts

Please refer to contributing.md for details on how to run the example package.