Issue #106 - Fix errors from html validation and add a note in README for test database

[kylelhk]

Change Summary

1. In home.html, move {% endblock %} to the last line of code.
2. In README, add a description about the test database under the Architecture section.

Change Form

• [x] The pull request title includes issue number and description.
• [x] The work done is summarised above.
• [ ] The code is commented and well formatted.
• [ ] Testing has been performed and documented above.

Other Information

N/A