fix: clarify test text in line with test functionality

[peterjgrainger]

Pre-Submission Checklist

• [✓ ] Your pull request targets the staging branch of freeCodeCamp.
• [ ✓] Branch starts with either fix/, feature/, or translate/ (e.g. fix/signin-issue)
• [✓ ] You have only one commit (if not, squash them into one commit).
• [ ✓] All new and existing tests pass the command npm test. Use git commit --amend to amend any fixes.

Type of Change

• [✓ ] Small bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds new functionality)
• Breaking change (fix or feature that would change existing functionality)
• Add new translation (feature adding new translations)

Checklist:

• [✓ ] Tested changes locally.
• Addressed currently open issue (replace XXXXX with an issue no in next line)

Closes #18256

Description

Clarify wording on React: Pass an Array as Props challenge to include that the p tag should include the list as a comma separated and updated the text displayed on failure of the test to include the same. This just helps the user figure out why the test is failing and clarifies what the test is actually testing for.

[Bouncey]

Nice catch, thanks @peterjgrainger

[Bouncey]

Thank you for your first contribution to freeCodeCamp/freeCodeCamp 👍 🎉 ✨