Manipulating initial HTML in Saber.md

You may want to manipulate initial HTML to inject some <link>s or <script>s, you can do this with setHead in saber-browser.js or head component option, but that adds bytes to your app runtime, Saber actually has an API that allows you to customize initial HTML.

Open saber-node.js:

exports.getDocumentData = documentData => {
  documentData.bodyScript += `<script>console.log('Run a script after your app code')</script>`
  return data
}

This hook is not well documented yet, for now you can check this file for all documentData properties.