README enhancements

[zenflow]

• general editing
• less verbose Features section
• simplify/reduce Basic Usage section
• explain ServiceConfig.ready function before Crash Handling (which should be changed to Custom Crash Handling)
• Shutting down: detail "optional behaviors"
• Shutting Down: "hint" -> Caveats (need for windowsCtrlCShutdown /w e.g. nodemon)

and enhancements to README for https://github.com/zenflow/composite-service-http-gateway