[3.10] bpo-41857: mention timeout argument units in select.poll() and select.depoll() doc-strings (GH-22406)

(cherry picked from commit 27df7566bc19699b967e0e30d7808637b90141f6)

Co-authored-by: Zane Bitter <zbitter@redhat.com>
diff --git a/Modules/selectmodule.c b/Modules/selectmodule.c
index 3ecd0c3..3afcb0e 100644
--- a/Modules/selectmodule.c
+++ b/Modules/selectmodule.c
@@ -564,6 +564,8 @@ select_poll_unregister_impl(pollObject *self, int fd)
 select.poll.poll
 
     timeout as timeout_obj: object = None
+      The maximum time to wait in milliseconds, or else None (or a negative
+      value) to wait indefinitely.
     /
 
 Polls the set of registered file descriptors.
@@ -574,7 +576,7 @@ report, as a list of (fd, event) 2-tuples.
 
 static PyObject *
 select_poll_poll_impl(pollObject *self, PyObject *timeout_obj)
-/*[clinic end generated code: output=876e837d193ed7e4 input=7a446ed45189e894]*/
+/*[clinic end generated code: output=876e837d193ed7e4 input=c2f6953ec45e5622]*/
 {
     PyObject *result_list = NULL;
     int poll_result, i, j;
@@ -888,6 +890,8 @@ select_devpoll_unregister_impl(devpollObject *self, int fd)
 /*[clinic input]
 select.devpoll.poll
     timeout as timeout_obj: object = None
+      The maximum time to wait in milliseconds, or else None (or a negative
+      value) to wait indefinitely.
     /
 
 Polls the set of registered file descriptors.
@@ -898,7 +902,7 @@ report, as a list of (fd, event) 2-tuples.
 
 static PyObject *
 select_devpoll_poll_impl(devpollObject *self, PyObject *timeout_obj)
-/*[clinic end generated code: output=2654e5457cca0b3c input=fd0db698d84f0333]*/
+/*[clinic end generated code: output=2654e5457cca0b3c input=3c3f0a355ec2bedb]*/
 {
     struct dvpoll dvp;
     PyObject *result_list = NULL;