Explain functional aspects of Nexus in the README

[eloydegen]

I am trying to figure out what Nexus actually does. The current README does not really help me understanding Nexus, and I think it should do that, in technical terms. The quotes from the main site do not tell me much:

• Publish and cache components in a central repository that connects natively to all popular package managers.
• Control the lifecycle of staged builds and custom metadata directly from your CI/CD server.
• Handle global workloads with dynamic storage, cleanup policies, and multi-node resiliency.

How does it communicate with other nodes, some TCP protocol? Does the software has a web interface? What packages managers are considered the popular ones here?

Questions like that would be great to answer in a README.