Fixed misspelling on Performace Best Practices --> very to vary

[claytoncollie]

Description of the Change

Fix a misspelling on Performance best practices --> very to vary

Checklist:

• [ x] I have read the CONTRIBUTING document.
• [ ] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my change.
• [ ] All new and existing tests passed.

Changelog Entry

Fixed misspelling on Performace Best Practices --> very to vary

[tlovett1]

Thank you!

[claytoncollie]

@tlovett1 You're too fast for me! :) I found a few more and will submit another PR. Lots of good info on this page. Thanks for publishing it.