Issue #21138: Change default reformat paragraph width to PEP 8's 72.

Author: terryjreedy

Lib/idlelib/config-main.def

@@ -59,7 +59,7 @@ font-bold= 0
 encoding= none
 
 [FormatParagraph]
-paragraph=70
+paragraph=72
 
 [Indent]
 use-spaces= 1

Misc/NEWS

@@ -186,7 +186,9 @@ Extension Modules
 IDLE
 ----
 
-- Issue 21284: Paragraph reformat test passes after user changes reformat width.
+- Issue #21139: Change default paragraph width to 72, the PEP 8 recommendation.
+
+- Issue #21284: Paragraph reformat test passes after user changes reformat width.
 
 - Issue #17654: Ensure IDLE menus are customized properly on OS X for
   non-framework builds and for all variants of Tk.