If you read https://www.postgresql.org/about/policies/sponsorship/ https://www.postgresql.org/about/policies/sponsorship/ you'll find that the list of sponsors

If you read https://www.postgresql.org/about/policies/sponsorship/ https://www.postgresql.org/about/policies/sponsorship/ you'll find that the list of sponsors is essentially a recognition for companies paying their employees to contribute to PostgreSQL. It isn't for contributing into a pot of money allowing some central PostgreSQL committee to hand out money for other things, like hiring people to do documentation.