Add concept text to readme (#20)
Add concept text to readme (#20)

* adds concept text to readme

* adds example code and fills last stubs

* adds note on Runnable properties of Zosma and fixes line width in some places

* add note on ExecutorService to README.md

* fix grammar in README.md

* add Rule doc, fix punctuation and newlines

* replace Pawn with ChessPiece

* Remove placeholders

delta-leonis/zosma,delta-leonis/zosma