doc: fix typos in README.md

[wstrm]

New Feature Submissions:

1. [x] Does your submission pass tests?
2. [x] Have you lint your code locally prior to submission?

Changes to Core Features:

• [x] Have you added an explanation of what your changes do and why you'd like us to include them?
• [x] Have you written new tests for your core changes, as applicable?
• [x] Have you successfully ran tests with your changes locally?

I crossed everything about tests because no infrastructure exists yet.