## Issue Addressed
Updated Lighthouse book on Section 2 and added some FAQs
## Proposed Changes
All changes are made in the book/src .md files.
## Additional Info
Please provide any additional information. For example, future considerations
or information useful for reviewers.
Co-authored-by: chonghe <tanck2005@gmail.com>
Co-authored-by: Michael Sproul <micsproul@gmail.com>