New PostgreSQL Books

Hello all!

I'm one of the developers working on the new PostgreSQL website, and while
reviewing for outdated information I noticed there's some new books
published in 2017 & 2018 that aren't in the Books database. Are there any
arguments against including these?

- https://bookauthority.org/books/new-postgresql-books
- https://bigmachine.io/products/a-curious-moon

Additionally, I think it'd be a great idea to have more versatile resources
provided to people looking to learn PostgreSQL. That seems to be the
biggest barrier preventing people from getting started, from conversations
I've had at conferences. So I'd like to include a new page under
"Documentation" labeled something like "Online Resources".

Some potential candidates for inclusion:

- http://schemaverse.com/
- http://www.postgresqltutorial.com/
- https://zaiste.net/posts/postgresql_primer_for_busy_people/
- http://postgresguide.com/
- http://www.tutorialspoint.com/postgresql/
- https://pgexercises.com/
- https://github.com/dhamaniasad/awesome-postgres
- http://books.goalkicker.com/PostgreSQLBook/

If you disagree with the idea, any of the suggestions, or if you have any
input on other resources/books to include please let me know.

Thanks!

--
Sarah Schnurr