added changelog

Author: AnnMarieW

CHANGELOG.md

@@ -2,6 +2,16 @@
 All notable changes to `dash` will be documented in this file.
 This project adheres to [Semantic Versioning](https://semver.org/).
 
+## [UNRELEASED]
+
+## Added
+- [2760](https://github.com/plotly/dash/pull/2760) New additions to dcc.Loading resolving multiple issues:
+  - `delay_show` and `delay_hide` props  to prevent flickering during brief loading periods (similar to Dash Bootstrap Components dbc.Spinner)
+  - `overlay_style` for styling the loading overlay,  such as setting  visibility and opacity for children
+  - `target_components` specifies components/props triggering the loading spinner
+  - `custom_spinner`  enables using a custom component for loading messages instead of built-in spinners
+  - `display`  overrides the loading status with options for "show," "hide," or "auto"
+
 ## [2.16.0] - 2024-03-01
 
 ## Fixed