Add missing period in distutils.dep_util.newer_group doc (GH-11003)

(cherry picked from commit c9566b8c454120e3d0ddb5ab970f262a6cd80077)

Co-authored-by: Andre Delfino <adelfino@gmail.com>
diff --git a/Doc/distutils/apiref.rst b/Doc/distutils/apiref.rst
index dccd7ce..8efeffb 100644
--- a/Doc/distutils/apiref.rst
+++ b/Doc/distutils/apiref.rst
@@ -941,7 +941,7 @@
 .. function:: newer_group(sources, target[, missing='error'])
 
    Return true if *target* is out-of-date with respect to any file listed in
-   *sources*  In other words, if *target* exists and is newer than every file in
+   *sources*.  In other words, if *target* exists and is newer than every file in
    *sources*, return false; otherwise return true. *missing* controls what we do
    when a source file is missing; the default (``'error'``) is to blow up with an
    :exc:`OSError` from  inside :func:`os.stat`; if it is ``'ignore'``, we silently