Add auto docs

[gwehrle]

Add automated documentation with Documenter.jl and publish it on github pages.

[kaat0]

• Include the file waterfountains.overpassql in the docs (mentioned in the README.md).
• Show different usages including parsing with JSON, CSV, and XML(?).

[gwehrle]

I added documentation. If you have time it would be helpful to review it.
For me showing useage with JSON CSV etc is not needed, but if you still think it is, I'll add it

[gwehrle]

Add different parsing as examples