Fix typos in Project Overview docs

[davidsemakula]

Description

Please include a summary of the change and which issue is fixed. Please also include relevant motivation and context.

Fixes a few typos in Project Overview docs

Fixes # (issue)

N/A

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• API change with a documentation update
• Additional test coverage
• Code cleanup or just keeping up with the latest Rustc nightly

N/A - Doesn't include any code changes

How Has This Been Tested?

N/A

Checklist:

• Fork the repo and create your branch from main.
• If you've added code that should be tested, add tests.
• If you've changed APIs, update the documentation.
• Ensure the test suite passes.
• Make sure your code lints.
• If you haven't already, complete your CLA here: https://code.facebook.com/cla