Fix formatting, typos, more in README

- Delete duplicated bombLens line
- Fix accidental link by wrapping in code markup
- Fix spelling of “except”, “compose”, “with”, “implementation”, “implementations”, “Bomberman” (spelled like [Bomberman (video game) – Wikipedia](https://en.wikipedia.org/wiki/Bomberman_%28video_game%29))
- Capitalize “Scala”
- Correct the placement of a comma