Macro for docstring of universal functions

[albinahlback]

Came to mind while comparing the current docstring of fmpz_poly_is_squarefree with fq_poly_is_squarefree: Given two similar functions, they should more or less have the same docstring.

An easy way to

• ensure consistency throughout FLINT docs,
• try to enforce a specific definition throughout FLINT,
• with less code,

would therefore be to have macros for such docstrings. Not sure how to achieve this in the Sphinx, but feels very achievable.

Very reasonable thing to do during the workshop.