bpo-37580: Fix typo in http.cookiejar documentation (GH-14731)

[bpo-37580](https://bugs.python.org/issue37580): Markup typo in http.cookiejar doc

https://bugs.python.org/issue37580
(cherry picked from commit b5bbb8a)

Co-authored-by: Milan Oberkirch <milan.oberkirch@geops.de>

Author: miss-islington

Doc/library/http.cookiejar.rst

@@ -153,7 +153,7 @@ contained :class:`Cookie` objects.
    the :class:`CookieJar`'s :class:`CookiePolicy` instance are true and false
    respectively), the :mailheader:`Cookie2` header is also added when appropriate.
 
-   The *request* object (usually a :class:`urllib.request..Request` instance)
+   The *request* object (usually a :class:`urllib.request.Request` instance)
    must support the methods :meth:`get_full_url`, :meth:`get_host`,
    :meth:`get_type`, :meth:`unverifiable`, :meth:`has_header`,
    :meth:`get_header`, :meth:`header_items`, :meth:`add_unredirected_header`