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

diff --git a/Lib/idlelib/editor.py b/Lib/idlelib/editor.py
index 89b7239..a667472 100644
--- a/Lib/idlelib/editor.py
+++ b/Lib/idlelib/editor.py
@@ -315,7 +315,7 @@
                   self.CodeContext(self).toggle_code_context_event)
 
     def _filename_to_unicode(self, filename):
-        """Return filename as BMP unicode so diplayable in Tk."""
+        """Return filename as BMP unicode so displayable in Tk."""
         # Decode bytes to unicode.
         if isinstance(filename, bytes):
             try: