README and docs update, so HACS shows the latest README. No changes to the panel itself since 3.0.2.
- A 40-second demo video on the docs home page; the README header links to it.
- New docs page Best experience: make HaCasa Nova your start page, hide the sidebar, tips for wall tablets.
- The Cards page shows a picture of every card.
HaCasa Nova is still a beta; known issues: #158.