Update CHANGELOG.md

CHANGELOG.md

@@ -7,6 +7,25 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [0.13.0] — 2024-09-03
 
+⚠️ BREAKING CHANGES: ⚠️
+
+Default exporting format is now GeoJSON instead of Owntracks-like JSON. This will allow you to use the exported data in other applications that support GeoJSON format. It's also important to highlight, that GeoJSON format does not describe a way to store any time-related data. Dawarich relies on the `timestamp` field in the GeoJSON format to determine the time of the point. The value of the `timestamp` field should be a Unix timestamp in seconds. If you import GeoJSON data that does not have a `timestamp` field, the point will not be imported.
+
+Example of a valid point in GeoJSON format:
+
+```json
+{
+  "type": "Feature",
+  "geometry": {
+    "type": "Point",
+    "coordinates": [13.350110811262352, 52.51450815]
+  },
+  "properties": {
+    "timestamp": 1725310036
+  }
+}
+```
+
 ### Added
 
 - GeoJSON format is now available for exporting data.