IDLE: Fix typos in docs and comments (GH-13749)

(cherry picked from commit d9677f36fe486e86bb86f2cd59cb7fc3804bdac1)

Co-authored-by: Xtreak <tir.karthi@gmail.com>
diff --git a/Lib/idlelib/undo.py b/Lib/idlelib/undo.py
index f048994..85ecffe 100644
--- a/Lib/idlelib/undo.py
+++ b/Lib/idlelib/undo.py
@@ -2,7 +2,7 @@
 
 from idlelib.delegator import Delegator
 
-# tkintter import not needed because module does not create widgets,
+# tkinter import not needed because module does not create widgets,
 # although many methods operate on text widget arguments.
 
 #$ event <<redo>>