README section for Ethereum.world instance

[josenriagu]

I think we should have a distinct section in the root README for Ethereum.world app

[felixboehm]

It would be good to cover the development getting started. It makes sense to direct that to the ethereum.world example, as it is most prominent.

Some input

• npm version needs to match. newest npm version is not building, with unresolved conflicts.
• configurations need explanation. I could not find hints on how to create a development config with a working invite service for signups.

[kenshyx]

Hey @felixboehm, thank you for your feedback!

Regarding your issues with npm, we've applied a patch this week that enables successful builds with npm v8.1.2 and node v16.13.0. We're running some test builds on circleCI with this configuration. Can you give it a try again? If the problem persists it would be great to have this captured in a issue on github or leave us here your configuration.
We will also update the github documentation as soon as possible!

Thank you for your interest in building ethereum world together! 🍻