[3.11] gh-101786: Clarify docs that asyncio.Server.sockets is a socket-like TransportSocket (GH-103877) (#103890)

Clarify that asyncio.Server.sockets is a socket-like TransportSocket
(cherry picked from commit 1c0a9c5a1c84bc334f2bde9d45676f19d9632823)

Co-authored-by: Carol Willing <carolcode@willingconsulting.com>