BUG: add note on creating Series from Series with dtype keyword

When creating Series from another Series `dtype` keyword is ignored. See GH #59060. Add note to the docstring to underline this behaviour to Series and DataFrame constructors.

Author: taranarmo

pandas/core/frame.py

@@ -531,6 +531,7 @@ class DataFrame(NDFrame, OpsMixin):
  will perform column selection instead.
  dtype : dtype, default None
  Data type to force. Only a single dtype is allowed. If None, infer.
+ If `data` is DataFrame then is ignored.
  copy : bool or None, default None
  Copy data from inputs.
  For dict data, the default of None behaves like ``copy=True``. For DataFrame

pandas/core/series.py

@@ -256,6 +256,7 @@ class Series(base.IndexOpsMixin, NDFrame): # type: ignore[misc]
  Data type for the output Series. If not specified, this will be
  inferred from `data`.
  See the :ref:`user guide <basics.dtypes>` for more usages.
+ If `data` is Series then is ignored.
  name : Hashable, default None
  The name to give to the Series.
  copy : bool, default False