Document Path.is_mount(), update Misc/ACKS and Misc/NEWS (#2980)

diff --git a/Misc/ACKS b/Misc/ACKS
index e0640c1..f1f6c14 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -886,6 +886,7 @@
 James Lee
 John J. Lee
 Thomas Lee
+Cooper Ry Lees
 Tennessee Leeuwenburg
 Luc Lefebvre
 Pierre Paul Lefebvre