patch 8.2.0875: getting attributes for directory entries is slow

Problem:    Getting attributes for directory entries is slow.
Solution:   Add readdirex(). (Ken Takata, closes #5619)
diff --git a/runtime/doc/usr_41.txt b/runtime/doc/usr_41.txt
index 2642e0b..0793a04 100644
--- a/runtime/doc/usr_41.txt
+++ b/runtime/doc/usr_41.txt
@@ -791,6 +791,7 @@
 	hostname()		name of the system
 	readfile()		read a file into a List of lines
 	readdir()		get a List of file names in a directory
+	readdirex()		get a List of file information in a directory
 	writefile()		write a List of lines or Blob into a file
 
 Date and Time:				*date-functions* *time-functions*