chore: update CHANGELOG.md

Author: bcakmakoglu

CHANGELOG.md

@@ -2,6 +2,24 @@
 
 All notable changes to this project will be documented in this file.
 
+## [1.40.0] - 2024-08-19
+
+[809a9a4](809a9a4e16ba4b8cae4159c259ec6a9da0f42954)...[538b03e](538b03ef6b94d252410cca563428eb8288eba711)
+
+### Bug Fixes
+
+- Correct controlled flow docs and replace `applyChanges` with `applyDefault` (#1574) ([876c198](876c19868f6b21f600c33b16192a5d2c1fb9256f))
+- Simplify event emit definitions to avoid hitting complexity limit of TS (#1585) ([ebc604d](ebc604d9803d53b8eb78ae68b727aa7b216ad6b3))
+- Only display grab cursor when panOnDrag is on left mouse button (#1586) ([e90f4cc](e90f4cca57415ad068eec777fa1bbe2f8b70bd75))
+
+### Documentation
+
+- Update layouting example (#1576) ([2976b11](2976b1102528a88f7b367d9c660130f2b9d078b9))
+
+### Refactor
+
+- Remove null as return type of data in `useNodesData` (#1575) ([1d772af](1d772af4a4c6424af570672372025617bebbc686))
+
 ## [1.39.3] - 2024-08-06
 
 [faeed3d](faeed3d6be9fe29c30a71ae09dbd056cc9445ad2)...[809a9a4](809a9a4e16ba4b8cae4159c259ec6a9da0f42954)