Refactor all READMEs

[nedtwigg]

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[nedtwigg]

Originally we just had java (eclipse and google-java-format) and generic, with undirected organic growth from that to a dozen different languages. So there was a ton of important information, but it was not organized. I reorganized it according to this principle:

• Languages
  • Java
    • (example showing default target and license, and the shortest-possible example of each step)
    • java-specific formatterstep 1
      • link to the formatter homepage, link to the formatter changelog
      • details of spotless DSL for that step
    • java-specific formatterstep 2
      • link to the formatter homepage, link to the formatter changelog
      • details of spotless DSL for that step
  • Groovy
    ....
• Language independent
  • Generic steps
  • License header
  • Line endings
  • Ratchet from, etc.

I apologize if I lost anything important, please feel free to put anything back in that I took out. I tried to be careful, but I'm sure some of the links and examples are broken.