message: Improve some docs for the extension API package
diff: Extraterm Extension API
  =======================
  -This module holds the TypeScript definitions of the Extraterm extension API.
  +This module holds the TypeScript definitions of the Extraterm extension API and is published as a packge up on npmjs.com.
  https://github.com/sedwards2009/extraterm
  +
  +Publishing
  +----------
  +
  +When this API changes it needs to be published.
  +
  +Steps:
  +* Bump the package version inside `package.json`.
  +* Commit that change.
  +* Run `yarn publish` to publish and have the password for npmjs ready.
  +* Done.
  