docs: fix extlinks error

docs/tutorials/client.rst

@@ -9,7 +9,7 @@ of the connection with your SMTP server. In this discussion we discuss ways to c
 
 By default Red Mail uses `STARTTLS <https://en.wikipedia.org/wiki/Opportunistic_TLS>`_ or opportunistic
 TLS in connecting to the SMTP server. You may also change this if needed by changing the 
-``cls_smtp`` to other SMTP client classes from `smtplib <https://docs.python.org/3/library/smtplib.html>`_
+``cls_smtp`` to other SMTP client classes from ::stdlib:`smtplib <smtplib.html>`
 in standard library.
 
 .. note::

redmail/email/sender.py

@@ -39,7 +39,7 @@ class EmailSender:
         User password to authenticate on the server.
     cls_smtp : smtplib.SMTP
         SMTP class to use for connection. See options 
-        from `Python smtplib docs <https://docs.python.org/3/library/smtplib.html>`_.
+        from :stdlib:`Python smtplib docs <smtplib.html>`.
     use_starttls : bool
         Whether to use `STARTTLS <https://en.wikipedia.org/wiki/Opportunistic_TLS>`_ 
         when connecting to the SMTP server.