Add Google Cloud to the Getting Started / Setup page

[voycey]

Would it be possible to add a GCP setup page to the Getting Started section, its super simple on GCP:

https://cloud.google.com/blog/products/application-development/using-node-red-with-google-cloud

Basically its just a case of launching an instance from a Docker Image with the rest default settings.

[hardillb]

Please feel free to open a Pull Request to add a section for Google Cloud. The information should all be in the update, not just a link to the blog post and should greatly improve on the Security section to actually say how apply adminAuth changes.