All examples should be tested

Reference to command, code snippet could be integrated using literalinclude.

For example:

  .. literalinclude:: ../appveyor.yml
     :language: yaml
     :start-after: scikit-ci-yml.rst: start
     :end-before: scikit-ci-yml.rst: end
     :emphasize-lines: 2, 5, 8, 11

The start-after / start-before are optional, they allow to limit the focus on a section of a script. In this case, appveyor.yml