Add open graph image and improve SEO

[Hugoo]

Source: https://www.opengraph.xyz/url/https%3A%2F%2Fwallet.page%2Fwallet%2Fsummary

The current website does not have an open graph image.

• [ ] Add opengraph image for the homepage (we need to decide what image, and who makes it)
• [ ] Change title from: "Walletbeat" to "Wallet Beat - The state of the ethereum wallets ecosystem"

To consider: add a custom, opengraph image per wallet?

For reference: L2Beat:

Source: https://www.opengraph.xyz/url/https%3A%2F%2Fl2beat.com%2Fscaling%2Fsummary

[polymutex]

This should probably be done as part of #80, as one of the design materials.