Write docs based on the four pillars of documentatoin

[felixcremer]

This is a nice explanation of the four functions of documentation: https://documentation.divio.com/introduction/ The four parts are: Tutorials How-to guides Reference Explanation

From our discussion earlier, the next steps for the documentation are:

• [ ] Write a tutorial @meggart
• [ ] Write a how to use Tiff files (or arbitrary files from GDAL) in YAXArrays @felixcremer
• [x] Exposing the docstrings as a reference guide @felixcremer See #41
• [ ] Write a performance tips section to explain the influence of chunking and parallel computation on the performance. @meggart

I'd like to use this issue to track the development of the documentation.

[felixcremer]

Check for public tiff files to write the gdal tutorial. Maybe use public data used by https://github.com/e-sensing/sits

[lazarusA]

new docs, cover most of these things if not all.