Make the example for --as_type more similar to a real use case

[merkys]

This PR attempts to provide more "real-world" usage example of --as_type: single entry response should be validated as such. Prior to this change, single entry response was shown to be validated as a collection, what would definitely fail.

[ml-evs]

Thanks for this @merkys!

[codecov]

Codecov Report

Merging #398 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #398   +/-   ##
=======================================
  Coverage   89.62%   89.62%           
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  Files          55       55           
  Lines        2459     2459           
=======================================
  Hits         2204     2204           
  Misses        255      255           

Flag	Coverage Δ
#unittests	89.62% <ø> (ø)

Impacted Files	Coverage Δ
optimade/validator/__init__.py	10.00% <ø> (ø)

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[CasperWA]

Yeah. The issue with this is that the type (even for a single entry endpoint object) is still structures. But I guess we should clarify this in the documentation of the validator. I think having the difference in plural vs. singular here makes a lot of sense.

[ml-evs]

Yeah. The issue with this is that the type (even for a single entry endpoint object) is still structures. But I guess we should clarify this in the documentation of the validator. I think having the difference in plural vs. singular here makes a lot of sense.

Agreed, I'm going to add a validator docs section and further improve the help strings. In an upcoming PR, which I guess is a pre-overhaul before we actually overhaul the validator :P