Prepeare Documentation for Release

[LKaemmerling]

We need to prepare the documentation for the release.

This PR polish the readme of the repo and the documentation on read the docs (rtd).

First of all we should specify the scope of the readme as "for hcloud-python developers".

The docs on rtd is for users of the hcloud-python module, so we should start with some easy examples and a basic introduction. Then we should list all steps needed for the installation.

I also removed the authors.md, because we didn't have it elsewhere in our repositories.

This is just a first draft of how we could polish the documentation. What do you think about this?

[LKaemmerling]

You can see the generated documentation on:
https://hcloud-python.readthedocs.io/en/documentation/

[LD250]

1. At the moment, we have only two *.md files: CHANGELOG.md and CONTRIBUTING.md. Everything else is *.rst. Should we move completely to *.rst?

2. Is usage.rst up to date?

3. Autogenerated package documentation looks a bit messy. We should think about better structure. One option is to create this structure manually, (Example: https://github.com/requests/requests/blob/master/docs/api.rst)

4. We can use this link as a guide for the next steps
   https://realpython.com/documenting-python-code/

[LKaemmerling]

@LD250 i think we are ready here. Can you have a look over it?
@thcyron can you have a look too? What do you think about the proposal? https://hcloud-python.readthedocs.io/en/documentation/

[LD250]

I like the table of content and I think docs look good for launch. Please merge this one.

I think we should consider moving to the docstrings at some point. In this way, documentation will be more maintainable and will be available on only on readthedocs but in the code base as well.

I believe #13 will be the next step in documentation improvement.

[thcyron]

For me, #13 is a requirement for a version 1.0 release. People will look at our code and a total lack of in-code documentation won’t give them the feeling that our library is mature and high-quality.