DOC: Remove incorrect periods at the end of parameter types
There are around 20 functions and methods in pandas that have an invalid period at the end of the parameter types, as reported by `./scripts/validate_docstrings.py --errors=PR05`:
```
pandas.read_clipboard: Parameter "sep" type should not finish with "."
pandas.Series.astype: Parameter "copy" type should not finish with "."
pandas.Series.astype: Parameter "errors" type should not finish with "."
pandas.Series.reorder_levels: Parameter "order" type should not finish with "."
pandas.Series.str.lstrip: Parameter "to_strip" type should not finish with "."
pandas.Series.str.match: Parameter "na" type should not finish with "."
pandas.Series.str.rstrip: Parameter "to_strip" type should not finish with "."
pandas.Series.str.strip: Parameter "to_strip" type should not finish with "."
pandas.DataFrame.astype: Parameter "copy" type should not finish with "."
pandas.DataFrame.astype: Parameter "errors" type should not finish with "."
pandas.Panel.astype: Parameter "copy" type should not finish with "."
pandas.Panel.astype: Parameter "errors" type should not finish with "."
pandas.RangeIndex: Parameter "start" type should not finish with "."
pandas.MultiIndex.sortlevel: Parameter "sort_remaining" type should not finish with "."
pandas.DatetimeIndex.to_series: Parameter "keep_tz" type should not finish with "."
pandas.api.types.is_dict_like: Parameter "obj" type should not finish with "."
pandas.api.types.is_file_like: Parameter "obj" type should not finish with "."
pandas.api.types.is_list_like: Parameter "obj" type should not finish with "."
pandas.api.types.is_named_tuple: Parameter "obj" type should not finish with "."
pandas.api.types.is_iterator: Parameter "obj" type should not finish with "."
pandas.api.types.is_re: Parameter "obj" type should not finish with "."
pandas.api.types.is_re_compilable: Parameter "obj" type should not finish with "."```
```

The idea is that this is correct:
```
def foo(param1):
    """
    Parameters
    ----------
    param1 : str
        Parameter 1 description.
    """
```

But this is what we have (not that in the second case, there is a period after `str`, which shouldn't be there).

```
def foo(param1):
    """
    Parameters
    ----------
    param1 : str.
        Parameter 1 description.

    """
```

We should remove the periods, and make sure that `./scripts/validate_docstrings.py --errors=PR05` does not report anything.