Update README with instructions

[abstractalgo]

Add details on how to add new cards, or features, or languages.

• submit a PR that will be reviewed
• license information
• NextJS + Vercel
  • automatic preview builds and CI/CD
• adding new topic
• adding new technology
• code of conduct file
• best practices
  • think about the readers' level of familiarity with the material (prefer more details and explanations over obfuscation and hard to understand, cryptic things)
  • stay consistent in writing style and styling
  • if you're making a change, think about its effect on technologies in the same topic - do you need to update them as well?
  • try not to post a topic with only one technology if you can - you may be an expect in one, but not in multiple areas, and that is fine, but makes it that much less useful for other people, so think about extending with at least one more tech for the comparison
• don't:
  • remove or reorder someone else's content just for the sake of your own promotion
  • don't write in "sales language" - the website is not there to promote and market things, but primarily to help out by giving very concrete, pragmatic information and steps
• it's ok:
  • remove and/or reorder things based on the popularity of technologies, for the sake of staying up to date with the latest trends
  • refresh the content with the latest instructions and steps (if it's useful, maybe even keep the older version around)
  • add mentions of your personal projects, as long as they focus on the specific topic sufficiently (if not, maybe even consider creating a new topic) and have some tangible traction so that readers don't get spammed and information gets diluted, losing all point