Fix documentation of models.circuit.Circuit

[renatomello]

Checklist:

• Reviewers confirm new code works as expected.
• Tests are passing.
• Coverage does not decrease.
• Documentation is updated.

[alecandido]

Just to understand: was there any issue with the testcode directive?

[renatomello]

testcode does not display the code in the compiled documentation, leaving the example blank in the doc https://qibo.science/qibo/stable/api-reference/qibo.html#qibo.models.circuit.Circuit + all these different initializations are being tested in the regular tests anyway.

[alecandido]

Ok. I'm not sure why it is happening, since in principle even testcode blocks should be shown, according to Sphinx
https://www.sphinx-doc.org/en/master/usage/extensions/doctest.html#directive-testcode

By default it is shown as a highlighted code block.

(there is an explicit attribute :hide: to avoid showing it).

I wonder why... but a workaround is still better than an empty block. Thanks for the fix!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.68%. Comparing base (4588671) to head (f5b93b4).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1544   +/-   ##
=======================================
  Coverage   99.68%   99.68%           
=======================================
  Files          80       80           
  Lines       11607    11607           
=======================================
  Hits        11571    11571           
  Misses         36       36           

Flag	Coverage Δ
unittests	99.68% <ø> (ø)

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[alecandido]

In principle, you could replace this with:

    Example::

The double colon is a short-cut in Sphinx for a code block, with the default syntax (which in our case, the default, it's just Python).
https://www.sphinx-doc.org/en/master/usage/restructuredtext/basics.html#literal-blocks