Extract yaml used in documentation into files

[dgageot]

This creates a shortcode to embed yaml configuration fragments into the documentation.
The fragments are parsed by a unit test to ensure that each of them is a valid configuration.

This helped fix a bug in one of the yaml files.

Signed-off-by: David Gageot david@gageot.net

[codecov-io]

Codecov Report

Merging #1593 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1593   +/-   ##
=======================================
  Coverage   46.51%   46.51%           
=======================================
  Files         118      118           
  Lines        5044     5044           
=======================================
  Hits         2346     2346           
  Misses       2464     2464           
  Partials      234      234

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[balopat]

LGTM, thanks, this is awesome!
The only tiny nit I have that as it is the readFile shortcode always adds a yaml syntaxed code.
We could rename it to includeYaml or maybe we can parametrize the language and add the yaml tag on readFile as a parameter...

[dgageot]

@balopat Thanks! I'll add type argument when it's needed