Update typos in README.md

[aladesawe]

Why is this pull request needed and what does it do? Typo updates in README

Which issues (if any) are related? N/A

Checklist:

• I have bumped the chart version according to versioning.
• I have updated the chart changelog with all the changes that come with this pull request according to changelog.
• Any new values are backwards compatible and/or have sensible default.
• I have signed off all my commits as required by DCO.

Changes are automatically published when merged to main. They are not published on branches.

Note on DCO

If the DCO action in the integration test fails, one or more of your commits are not signed off. Please click on the Details link next to the DCO action for instructions on how to resolve this.

[hagaibarel]

Thanks for the PR!

Please take a look at the https://github.com/coredns/helm/blob/master/CONTRIBUTING.md guide and fix the failing checks so we can get your changes merged