[3.14] gh-135142: Initial 3.15 News3.txt entries (GH-144200) (#144201)

(cherry picked from commit 29f1e77)

Author: terryjreedy

Lib/idlelib/News3.txt

@@ -1,9 +1,20 @@
+What's New in IDLE 3.14.z
+(since 3.14.0)
+Released after 2025-10-07
+=========================
+
+
+gh-143774: Better explain the operation of Format / Format Paragraph.
+Patch by Terry J. Reedy.
+
+gh-139742: Colorize t-string prefixes for template strings in IDLE,
+as done for f-string prefixes.  Patch by Anuradha Agrawal.
+
 What's New in IDLE 3.14.0
 (since 3.13.0)
 Released on 2025-10-07
 =========================
 
-
 gh-129873: Simplify displaying the IDLE doc by only copying the text
 section of idle.html to idlelib/help.html. Patch by Stan Ulbrych.