Fix a couple documentation typos. (GH-10498)


reproduciblity -> reproducibility
PyPA are the group -> PyPA is the group
(cherry picked from commit 0dc1e45dfd242493ecdac5dbcad51dbc8f922de7)

Co-authored-by: Windson yang <wiwindson@outlook.com>
diff --git a/Doc/installing/index.rst b/Doc/installing/index.rst
index 7a69869..8af828b 100644
--- a/Doc/installing/index.rst
+++ b/Doc/installing/index.rst
@@ -48,7 +48,7 @@
   repository of open source licensed packages made available for use by
   other Python users.
 * the `Python Packaging Authority
-  <https://www.pypa.io/>`__ are the group of
+  <https://www.pypa.io/>`__ is the group of
   developers and documentation authors responsible for the maintenance and
   evolution of the standard packaging tools and the associated metadata and
   file format standards. They maintain a variety of tools, documentation,