Issue #25895: Enable WebSocket URL schemes in urllib.parse.urljoin

Patch by Gergely Imreh and Markus Holtermann.
diff --git a/Doc/library/urllib.parse.rst b/Doc/library/urllib.parse.rst
index c6de230..007e4da 100644
--- a/Doc/library/urllib.parse.rst
+++ b/Doc/library/urllib.parse.rst
@@ -25,7 +25,7 @@
 ``gopher``, ``hdl``, ``http``, ``https``, ``imap``, ``mailto``, ``mms``,
 ``news``, ``nntp``, ``prospero``, ``rsync``, ``rtsp``, ``rtspu``, ``sftp``,
 ``shttp``, ``sip``, ``sips``, ``snews``, ``svn``, ``svn+ssh``, ``telnet``,
-``wais``.
+``wais``, ``ws``, ``wss``.
 
 The :mod:`urllib.parse` module defines functions that fall into two broad
 categories: URL parsing and URL quoting. These are covered in detail in