Update instructions for complex-number exercise

Hi, I made a PR to update the description of an exercise and it was automatically closed:

I understand all the contributions are in pause now, but I leave this message here in case someone wants to pick it up.

Hi and welcome!

For most tracks we recommend discussing any changes here in the forum first and reaching an agreement before making any changes.

And since this concerns the instructions: Here on Exercism the exercises start with a language-agnostic description and some tests in JSON format in the problem-specification repository. Then they get translated to the actual tracks.
So in almost all cases changes to the instructions should be discussed here on the forum first and then applied to the problem specification before these modifications get applied to all tracks. That’s a little bit more effort but it prevents the exercises on the various tracks from drifting apart.

See also, Suggesting Exercise Improvements | Exercism's Docs

thanks for the reply! I clicked on the “edit via github” link at the bottom of the page. thanks for pointing to the true data source.