docs: clarify the TS option's defaults (#316)
docs: clarify the TS option's defaults (#316)

- "latest 2.x" is no longer accurate and quite outdated (we're on 4.x
  now), so just say it's the peerDep instead
  - @rollup/plugin-typescript calls the default a peerDep too:
    https://github.com/rollup/plugins/tree/master/packages/typescript#typescript

- be more specific that you can pass in a different version or fork of
  TS (like `ttypescript`) through this option
  - follow-up to 8ec49c78f523687deaf6816bc2ea320f16e325c7

- auto-trim some whitespace-only lines
  - my editor does this automatically, and most of the README has
    trimmed whitespace anyway, so this keeps it consistent
ezolenko/rollup-plugin-typescript2,ezolenko/rollup-plugin-typescript2