update compiler configs and docs

[sisp]

It seems using different compiler settings for MobX 4 and 5/6 isn't necessary. Do you think this is generally valid? At least the test suite passes.

[netlify]

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[codecov]

Codecov Report

Merging #421 (d5faaba) into master (17ffa8e) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #421   +/-   ##
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  Coverage   90.93%   90.93%           
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  Files         179      179           
  Lines        6388     6388           
  Branches     1168     1157   -11     
=======================================
  Hits         5809     5809           
  Misses        542      542           
  Partials       37       37           

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[xaviergonz]

I don't know, I think those config were taken directly from mobx docs, so while they might work with keystone they might not work if you use decorators for mobx itself

[sisp]

Okay, I'll investigate a bit further.