Fix typos

[henryjw]

Related issue

None.

Proposed changes

Fixed some typos I noticed while reading the Readme.

Checklist

• I have read the contributing guidelines
• I have read the security policy
• I confirm that this pull request does not address a security vulnerability. If this pull request addresses a security
  vulnerability, I confirm that I got green light (please contact [email protected]) from the maintainers to push the changes.
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation within the code base (if appropriate)
• I have documented my changes in the developer guide (if appropriate)

Further comments

Many of the checkboxes in the checklist aren't selected since this PR only changes typos in the documentation. No code changes were made.

[claassistantio]

All committers have signed the CLA.

[aeneasr]

Thank you!