(#17158) clarify documentation on behavior of replace toward symlinks in file type

Without this patch applied the behavior of replace toward symlinks in the file type isn't
made explicit. This is a problem because some other parameters note differences where
symlinks are concerned, and the lack of mention of symlinks in replace creates a sense
of ambiguity for some users.

This patch clarifies the behavior of replace toward symlinks by improving the description
docstring.