docs: clarify timeout parameter uses seconds in Session.request (#6994)

Author: killerdevildog

src/requests/sessions.py

@@ -535,7 +535,7 @@ def request(
             for multipart encoding upload.
         :param auth: (optional) Auth tuple or callable to enable
             Basic/Digest/Custom HTTP Auth.
-        :param timeout: (optional) How long to wait for the server to send
+        :param timeout: (optional) How many seconds to wait for the server to send
             data before giving up, as a float, or a :ref:`(connect timeout,
             read timeout) <timeouts>` tuple.
         :type timeout: float or tuple