Update UPGRADING

LamentXU123 · LamentXU123 · commit a967ff1ecab7 · 2026-03-20T19:56:48.000+08:00
diff --git a/UPGRADING b/UPGRADING
@@ -252,6 +252,8 @@ PHP 8.6 UPGRADE NOTES
 
 - JSON:
   . Improve performance of encoding arrays and objects.
+  . Improved performance of indentation generation in json_encode()
+    when using PHP_JSON_PRETTY_PRINT.
 
 - Standard:
   . Improved performance of array_fill_keys().
