DOC: shift argument in `Series.shift()` is not used

[Dr-Irv]

Pandas version checks

• I have checked that the issue still exists on the latest versions of the docs on main here

Location of the documentation

https://pandas.pydata.org/docs/reference/api/pandas.Series.shift.html#pandas.Series.shift

Documentation problem

The documentation for Series.shift() documents the parameter suffix, but it has no effect in the code.

Suggested fix for documentation

I think the suffix argument should be removed from the docs.

[jorisvandenbossche]

It's used by the DataFrame.shift implementation, and both methods use a shared docstring .. But we can mention that the keyword is ignored for Series (like there is also a mention for axis)