Adding notes about Request's timeout behavior.

docs/user/advanced.rst

@@ -910,7 +910,8 @@ Timeouts
 --------
 
 Most requests to external servers should have a timeout attached, in case the
-server is not responding in a timely manner. Without a timeout, your code may
+server is not responding in a timely manner. By standard, requests do not time
+out unless a timeout value is set explicitly. Without a timeout, your code may
 hang for minutes or more.
 
 The **connect** timeout is the number of seconds Requests will wait for your

docs/user/quickstart.rst

@@ -497,7 +497,8 @@ seconds with the ``timeout`` parameter::
     ``timeout`` is not a time limit on the entire response download;
     rather, an exception is raised if the server has not issued a
     response for ``timeout`` seconds (more precisely, if no bytes have been
-    received on the underlying socket for ``timeout`` seconds).
+    received on the underlying socket for ``timeout`` seconds). If NO timeout is specified explicitly, requests do
+    not time out.
 
 
 Errors and Exceptions