bpo-39183: Fix formatting in library/ensurepip (GH-17787)

Remove extra space to fix formatting and avoid from splitting text in to strings.

https://bugs.python.org/issue39183
(cherry picked from commit 149175c)

Co-authored-by: Rafael Fontenelle <rffontenelle@users.noreply.github.com>

Author: miss-islington

Doc/library/ensurepip.rst

@@ -74,7 +74,7 @@ options:
   script will *not* be installed.
 
 * ``--default-pip``: if a "default pip" installation is requested, the
-   ``pip`` script will be installed in addition to the two regular scripts.
+  ``pip`` script will be installed in addition to the two regular scripts.
 
 Providing both of the script selection options will trigger an exception.