fix(curriculum): clarify .toFixed() explanation and examples

[domsteindl]

Checklist:

• I have read and followed the contribution guidelines.
• I have read and followed the how to open a pull request guide.
• My pull request targets the main branch of freeCodeCamp.
• I have tested these changes either locally on my machine, or GitHub Codespaces.

Closes #66991

Further clarify explanation of how .toFixed() acts when no argument is provided.
To accomplish this i moved the example as for when no argument is provided further up and also altered the explanation of it

I have tested the change on my local setup of ffc

Before

After

[github-actions]

Hi there,

Thanks for opening this pull request.

The automated checks found some issues:

Linked Issue: The linked issue has not been triaged yet, and a solution has not been agreed upon. Once the issue is open for contribution, you are welcome to update this pull request to reflect the issue consensus. Until then, we will not be able to review your pull request.

---

Join us in our chat room or our forum if you have any questions or need help with contributing.

[gikf]

Hi there,

Thanks for creating this pull request.

The linked issue has not been triaged yet, and a solution has not been agreed upon. Once the issue is open for contribution, you are welcome to update this pull request to reflect the issue consensus. Until the issue is open for contribution, we will not be able to review your pull request.