text: Title: [DOC] Update Pull Request Template with `netlify` option
  Body: # Brief Description of Fix
  
  <!-- Please describe the fix in terms of a "before" and "after". In other words, what's not so good about the current docs
  page, and what you would like to see it become.
  
  Example starter wording is provided. -->
  
  Currently, the recommended approach for reviewing documentation updates is to build the docs locally. This may still be the recommended approach, but a note should be included that lets developers know that they can preview the docs from the PR checks as well (with the new `netlify` inclusion).
  
  I would like to propose a change, such that now the docs have examples on how to use the `netlify` doc previews from a PR. 
  
  # Relevant Context
  
  <!-- Please put here, in bullet points, links to the relevant docs page. A few starting template points are available
  to get you started. -->
  
  - [Link to exact file to be edited](https://github.com/ericmjl/pyjanitor/blob/dev/.github/pull_request_template.md)
  - Maybe we want to add a line to the `CONTRIBUTING.rst` files as well? 🤷‍♂️ 
  