chown.2: When file owner or group is changed, file capabilities are cleared

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man2/chown.2

@@ -142,6 +142,10 @@ bit is not set) the
 .B S_ISGID
 bit indicates mandatory locking, and is not cleared by a
 .BR chown ().
+
+When the owner or group of an executable file is changed (by any user),
+all capability sets for the file are cleared.
+.\"
 .SS fchownat()
 The
 .BR fchownat ()