Move to `examples/` dir

[bpmct]

Move this repo into the Coder project with examples/. Let's create separate repos for Railway, Heroku, etc.

[bpmct]

I don't plan on doing this in the next few months, but it is planned.

[matifali]

I have a few suggestions,

1. Create separate repos under https://github.com/coder like GitHub does for codespaces

See: https://github.com/orgs/github/repositories?q=codespaces&type=source&language=&sort=

2. Instead of creating different repos, we can put each in a different branch.

heroku --> branch heroku

railway --> branch railway

I prefer 1st option.

[matifali]

We do not need a repo or directory for railway anymore. See #98