DOC: special: Updates for smirnov and smirnovi (#17243)
DOC: special: Updates for smirnov and smirnovi (#17243)

* Copy-edit the docstrings: fix section order, fix long
  lines (PEP8), use f-strings, etc.  In smirnov, use a literal
  array instead of random, and update the plot.
* Add Examples to smirnovi.

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