Purge by Cache Tag is available on all plans

Problem/Motivation

The project page → as well as the README states that purging by cache tag is not available on plans other than Enterprise. However, this is no longer the case.

Steps to reproduce

N/A

Proposed resolution

Update the documentation to reflect the updated policy / pricing.

Remaining tasks

1. Update project description
2. Update README

User interface changes

N/A

API changes

Cache Tag purge requests will succeed now on any plan.

Data model changes

N/A