Fix major/minor issues

[khd33j]

This PR fixes some minor issues.

• [x] Add the favicon to about.html
• [x] Correct all the links on learn.html (including styles.css)
• [x] Delete newfavicon.svg
• [x] Move the logo to the top-left
• [x] Move the nav-links to the middle on index.html

Let me know if I should make any other changes.

Requesting a review from @codingkatty