Add VSCode setup instructions

[andyw8]

I had a lot trouble getting prettier working with VS Code. Initially I was trying to use the Ruby gem, but it seems the npm library is a better choice.

The approach I describe is based on @coisnepe's comment in #113.

[coisnepe]

// optional isn't valid json and messes up syntax highlighting

[andyw8]

It's valid in VS Code's settings config but I'll remove it.

[Petercopter]

Thanks for this, I thrashed around a lot with the npm package vs the gem as well. I was wondering whether there should also be instructions for how this interacts with the Ruby VSCode extension https://marketplace.visualstudio.com/items?itemName=rebornix.Ruby

I would imagine a lot of people have that installed as well. I THINK I finally got everybody playing nice together by adding

"ruby.lint":{}

To the VSCode config or maybe just remove it altogether. Before I had

  "ruby.lint": {
    "rubocop": {
      "forceExclusion": true,
      "useBundler": true // enable rubocop via bundler
    }
  },

Edit: Maybe "ruby.format": false as well...

[Jonic]

Just chiming in to say that I followed the steps in this PR and I'm VERY happy with the results! Thanks very much!

[joshunger]

I'd love to see this in the README however I don't think[ruby] is necessary if you have "editor.defaultFormatter": "esbenp.prettier-vscode". I don't think you need the third bullet.