Docs: Railway tutorial

[paulrobertlloyd]

This is the service I am currently using, so just need to remind myself how I set it up and write it down!

• Add tutorial for setting up an Indiekit server on Railway (adding GitHub and MongoDB components to a project)
• Create a deploy button/project template: https://railway.app/template/gEboK6
• Investigate Open Source Kickback scheme (Indiekit is eligible) – Happens automatically with the above published template.

[paulrobertlloyd]

Note: Selecting a Railway template requires you to create a new repo, so you can’t add Indiekit to an existing repo. Make a note of this somewhere, and consider this as a factor when writing guide.