Issue #12955: Change the urlopen() examples to use context managers where appropriate.

Patch by Martin Panter.
diff --git a/Doc/faq/library.rst b/Doc/faq/library.rst
index d71a9b4..064728f 100644
--- a/Doc/faq/library.rst
+++ b/Doc/faq/library.rst
@@ -687,7 +687,8 @@
    ### connect and send the server a path
    req = urllib.request.urlopen('http://www.some-server.out-there'
                                 '/cgi-bin/some-cgi-script', data=qs)
-   msg, hdrs = req.read(), req.info()
+   with req:
+       msg, hdrs = req.read(), req.info()
 
 Note that in general for percent-encoded POST operations, query strings must be
 quoted using :func:`urllib.parse.urlencode`.  For example, to send