DOC Remove mentions of removed AUTHORS.rst file (#12262)

MANIFEST.in

@@ -4,6 +4,5 @@ recursive-include examples *
 recursive-include sklearn *.c *.h *.pyx *.pxd *.pxi
 recursive-include sklearn/datasets *.csv *.csv.gz *.rst *.jpg *.txt *.arff.gz *.json.gz
 include COPYING
-include AUTHORS.rst
 include README.rst
 

README.rst

@@ -34,7 +34,8 @@ SciPy and distributed under the 3-Clause BSD license.
 
 The project was started in 2007 by David Cournapeau as a Google Summer
 of Code project, and since then many volunteers have contributed. See
-the `AUTHORS.rst <AUTHORS.rst>`_ file for a complete list of contributors.
+the `About us <http://scikit-learn.org/dev/about.html#authors>`_ page
+for a list of core contributors.
 
 It is currently maintained by a team of volunteers.
 
@@ -143,7 +144,8 @@ Project History
 
 The project was started in 2007 by David Cournapeau as a Google Summer
 of Code project, and since then many volunteers have contributed. See
-the  `AUTHORS.rst <AUTHORS.rst>`_ file for a complete list of contributors.
+the  `About us <http://scikit-learn.org/dev/about.html#authors>`_ page
+for a list of core contributors.
 
 The project is currently maintained by a team of volunteers.