Update Rails guide to document how to make it work with health checks

[RDIL]

Out of the box, Railway's health check system doesn't work on Rails due to it not thinking you're using SSL.

https://discord.com/channels/713503345364697088/1199452911583903956/1199452911583903956

[kophyo54]

``Duplicate of #1012

[RDIL]

@kophyo54 the PR linked does not seem to at all be related?