docs: update changelog

Author: uerceg

CHANGELOG.md

@@ -1,3 +1,15 @@
+### Version 5.3.0 (April 17th 2025)
+#### Added
+- Added ability to initialize the SDK for the first session in delayed mode. You can start the SDK in the delayed mode by setting the `IsFirstSessionDelayEnabled` property on your `AdjustConfig` instance to `true`. To end the delay, make sure to call `EndFirstSessionDelay` method of `Adjust` instance. For more details about this feature, refer to the [official documentation](https://dev.adjust.com/en/sdk/unity/features/first-session-delay).
+- Added ability to send organic search referrer together with deep link. You can send it by setting the `Referrer` property of the `AdjustDeeplink` instance.
+- Added ability to disable SDK's interaction with `AppTrackingTransparency.framework` API. You can disable it by setting the `IsAppTrackingTransparencyUsageEnabled` property on your `AdjustConfig` instance to `false`.
+
+#### Native SDKs
+- [[email protected]][ios_sdk_v5.3.0]
+- [[email protected]][android_sdk_v5.3.0]
+
+---
+
 ### Version 5.1.3 (March 24th 2025)
 #### Fixed
 - Fixed null reference exceptions when migrating from pre 5.1.0 version (https://github.com/adjust/unity_sdk/issues/330).
@@ -1415,6 +1427,7 @@ Kudos to [Ivan](https://github.com/MatkovIvan) and [Evgeny](https://github.com/e
 [ios_sdk_v5.0.1]: https://github.com/adjust/ios_sdk/tree/v5.0.1
 [ios_sdk_v5.1.0]: https://github.com/adjust/ios_sdk/tree/v5.1.0
 [ios_sdk_v5.1.1]: https://github.com/adjust/ios_sdk/tree/v5.1.1
+[ios_sdk_v5.3.0]: https://github.com/adjust/ios_sdk/tree/v5.3.0
 
 [android_sdk_v3.5.0]: https://github.com/adjust/android_sdk/tree/v3.5.0
 [android_sdk_v4.1.0]: https://github.com/adjust/android_sdk/tree/v4.1.0
@@ -1471,6 +1484,7 @@ Kudos to [Ivan](https://github.com/MatkovIvan) and [Evgeny](https://github.com/e
 [android_sdk_v5.0.1]: https://github.com/adjust/android_sdk/tree/v5.0.1
 [android_sdk_v5.0.2]: https://github.com/adjust/android_sdk/tree/v5.0.2
 [android_sdk_v5.1.0]: https://github.com/adjust/android_sdk/tree/v5.1.0
+[android_sdk_v5.3.0]: https://github.com/adjust/android_sdk/tree/v5.3.0
 
 [windows_sdk_v4.12.0]: https://github.com/adjust/windows_sdk/tree/v4.12.0
 [windows_sdk_v4.13.0]: https://github.com/adjust/windows_sdk/tree/v4.13.0