Pinned date and fixed contributors directive (#27455)

Author: WillAyd

Diff for: doc/source/whatsnew/v0.25.0.rst

@@ -1,7 +1,7 @@
 .. _whatsnew_0250:
 
-What's new in 0.25.0 (April XX, 2019)
--------------------------------------
+What's new in 0.25.0 (July 18, 2019)
+------------------------------------
 
 .. warning::
 
@@ -1267,4 +1267,4 @@ Other
 Contributors
 ~~~~~~~~~~~~
 
-.. contributors:: v0.24.x..HEAD
+.. contributors:: 0.24.x..HEAD