bpo-37892: Use space indents in IDLE Shell (GH-25678)

Adding a newline to the prompt moves it out of the way of
user code input, which now starts at the left margin,
along with continuation lines.
diff --git a/Lib/idlelib/NEWS.txt b/Lib/idlelib/NEWS.txt
index ca4280f..83afe3e 100644
--- a/Lib/idlelib/NEWS.txt
+++ b/Lib/idlelib/NEWS.txt
@@ -4,6 +4,13 @@
 =========================
 
 
+bpo-37892: Change Shell input indents from tabs to spaces.
+
+bpo-37903: Move the Shell input prompt to a side bar.
+
+bpo-43655: Make window managers on macOS and X Window recognize
+IDLE dialog windows as dialogs.
+
 bpo-43283: Document why printing to IDLE's Shell is often slower than
 printing to a system terminal and that it can be made faster by
 pre-formatting a single string before printing.