Add module lookup and launch quick start

[DanielThomas]

Summary

• add an abridged quick start to the README
• show Maven artifact-to-module lookup
• show resolving and running JUnit Console by module name
• rely on the module main-class attribute rather than emitting an explicit main class

Validation

• ran the documented lookup with jig 0.15.0
• generated the documented argument file and launched java @junit.args --help
• ran git diff --check