DOC: 0.25 fixups
* fix tag for contributors
* fix 0.25.1 contributors
* remove orphan

Closes https://github.com/pandas-dev/pandas/issues/27687
thanks @TomAugspurger  Contributors section in 0.25.0 notes is still empty, see https://github.com/pandas-dev/pandas/issues/27687#issuecomment-544931258