[3.9] bpo-43723: Revert IDLE doc change (GH-25174)

[3.9] bpo-43723: Revert IDLE doc change (GH-25174) · python/cpython@56c76df

Original file line number	Diff line number	Diff line change
`@@ -732,7 +732,7 @@ intended to be the same as executing the same code by the default method,`
`732`	`732`	`directly with Python in a text-mode system console or terminal window.`
`733`	`733`	`However, the different interface and operation occasionally affect`
`734`	`734`	visible results. For instance, ``sys.modules`` starts with more entries,
`735`		-and ``threading.activeCount()`` returns 2 instead of 1.
	`735`	+and ``threading.active_count()`` returns 2 instead of 1.
`736`	`736`
`737`	`737`	`By default, IDLE runs user code in a separate OS process rather than in`
`738`	`738`	`the user interface process that runs the shell and editor. In the execution`