make README.md easier to parse

[mininmobile]

• separate "getting started" from deployment instructions for laypeople who simply want to use cinny
• break up deployment instructions so it is easier to interpret
• remove commands for the docker pulls, as they are on the respective repositories
• explain what hash routing is, link to all webserver config examples (assuming add example caddyfile #2227 is merged too)
• bold pgp key dropdown to make it stand out
• make the recommendation to use nvm a spiffy tip alert

[github-actions]

Thank you for your submission, we really appreciate it. Like many open-source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution. You can sign the CLA by just posting a Pull Request Comment same as the below format.

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I have read the CLA Document and I hereby sign the CLA

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[mininmobile]

I have read the CLA Document and I hereby sign the CLA ✅