bpo-28097: IDLE - Add Previous/Next History to Shell menu (GH-11325)

(cherry picked from commit c0381aaea4ad3e866bde70393c4f7efe9bcf3568)

Co-authored-by: Cheryl Sabella <cheryl.sabella@gmail.com>
diff --git a/Doc/library/idle.rst b/Doc/library/idle.rst
index ef9bd26..56d7c9f 100644
--- a/Doc/library/idle.rst
+++ b/Doc/library/idle.rst
@@ -235,6 +235,12 @@
 Restart Shell
   Restart the shell to clean the environment.
 
+Previous History
+  Cycle through earlier commands in history which match the current entry.
+
+Next History
+  Cycle through later commands in history which match the current entry.
+
 Interrupt Execution
   Stop a running program.