[PR #8953/51ea3b39 backport][3.11] Add clarification about auth param…

…eter in ClientSession (#8955)

**This is a backport of PR #8953 as merged into master
(51ea3b3).**

Co-authored-by: Maxim Zemskov <m.zemskov1@gmail.com>

CHANGES/6764.doc.rst

@@ -0,0 +1 @@
+Clarified that auth parameter in ClientSession will persist and be included with any request to any origin, even during redirects to different origins.  -- by :user:`MaximZemskov`.

docs/client_reference.rst

@@ -99,7 +99,10 @@ The client session supports the context manager protocol for self closing.
       Iterable of :class:`str` or :class:`~multidict.istr` (optional)
 
    :param aiohttp.BasicAuth auth: an object that represents HTTP Basic
-                                  Authorization (optional)
+                                  Authorization (optional). It will be included
+                                  with any request to any origin and will not be
+                                  removed, event during redirect to a different
+                                  origin.
 
    :param version: supported HTTP version, ``HTTP 1.1`` by default.