Add documentation for running and using the project

[yharby]

Hi there,

I'm trying to use the go-tileproxy project, but I'm having trouble getting it up and running. Unfortunately, there are no instructions or documentation available in the repository, and I'm not sure where to start.

I wondered if the developers could add some documentation on how to run and use the project, including any dependencies or configuration options that are needed. This would be really helpful for anyone who wants to use the project in the future.

If there's any specific information or examples that would be helpful to include in the documentation, please let me know and I'd be happy to provide additional feedback.

Thanks!