docs(readme): fix two typos and remove duplicate section

[joaopalmeiro]

Hi! 👋

• [x] I understand that this repository is auto-generated and my pull request may not be merged

Changes being requested

• Fix two typos in the README file.
• Remove the duplicate section ## Realtime API from the README file (let me know if you have a preference on which of the two versions to remove, I opted for the second one).

Thanks!