fix(hmr): allow disabling md cache during dev

[brc-dd]

closes #117

To make HMR work with markdown includes or imported code snippets, add this to your config file:

export default {
  markdown: {
    cache: false
  }
}

It won't affect build performance, but might degrade dev perf slightly (~100ms, if you do undo/redo multiple times).

Alternatively, you can just press r on the terminal. But it's not good DX and it performs full page reload.