docs: Fix links to Jest docs

[msmolens]

What:

Update several out-of-date links to Jest configuration and matcher docs in README.md.

Why:

The original links redirect to the correct pages, but lose the anchor (e.g. #setupfilesafterenv-array). The updated links navigate to the correct location within each page.

Checklist:

• [x] Documentation
• [ ] Tests N/A
• [ ] Updated Type Definitions N/A
• [x] Ready to be merged