bpo-41858: Clarify line in optparse doc (GH-22407)

The existing line is easily read as being incomplete.
(cherry picked from commit 00eb063)

Co-authored-by: Emmanuel Arias <[email protected]>

Author: miss-islington

Doc/library/optparse.rst

@@ -55,7 +55,7 @@ equivalent to the above example::
    <yourscript> -q -foutfile
    <yourscript> -qfoutfile
 
-Additionally, users can run one of  ::
+Additionally, users can run one of the following ::
 
    <yourscript> -h
    <yourscript> --help