Added aws-node-heroku-postgres example.

[mattwelke]

I created this example for a blog post when experimenting with connecting AWS Lambda (us-east-1 region) and Heroku Postgres (in the United States region) together for a free tier serverless app that used PostgreSQL as its data layer. When I shared the blog post on the Slack channel of my local Serverless group, they suggested I add it to the official examples repo.

Feel free to let me know if there are any style changes etc to make to help it fit in in this repo.

Side note: As per the PR guide, I ran npm run lint but it returned exit code 1 because a lot of the examples already in here already don't pass linting, for example by having 12 space indentation in areas instead of 4.

[sebito91]

Don't forget to run npm run docs from the examples folder, it'll update the contributors documentation and pass the CI/CD requirements.

[mattwelke]

@sebito91 Done!

[pmuens]

Great example! Thanks for working on this @Welkie 🙌 💯

LGTM

/cc @eahefnawy