Add agriculture use-case to documentation

[sebastianstock]

This adds the description for the agricultural use-case as a showcase to the documentation.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (4473e4c) 84.92% compared to head (1eb6a1a) 84.92%.
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #528   +/-   ##
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  Coverage   84.92%   84.92%           
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  Files         200      200           
  Lines       26385    26385           
=======================================
  Hits        22408    22408           
  Misses       3977     3977           

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[arbimo]

@sebastianstock I have changed the image links from html to markdown syntax, otherwise they are not picked up by sphynx when building the doc. (You can look in the contributors's guide section of the doc to see how to preview changes).

If you want to rescale the images, the best option is to rescale them directly (it is also better for bandwidth). But you can also submit the document in reStructuredText that has more options to configure rendering.

Let me know if you want to update the PR or if it should go in as it is.

[sebastianstock]

Dear @arbimo, thanks for fixing the links and the hint about the image size. I have rescaled the images and checked it locally. Now it looks fine.