Update README and changelog with runtime.6 release

Author: Insality

CHANGELOG.md

@@ -61,3 +61,9 @@ Initial resease!
 - Refactor the animation playback system, should be more performant
 - Fix for `is_editor_only` key field
 - Various fixes
+
+
+## Version v6
+- Fix [#23](https://github.com/Insality/panthera/issues/23) Sprite image change animation does not work in nested collection
+- Fix [#20](https://github.com/Insality/panthera/issues/20) panthera.stop() does not work correctly with animations with multiple tween keys
+

README.md

@@ -35,7 +35,7 @@ https://github.com/Insality/defold-tweener/archive/refs/tags/5.zip
 **[Panthera Runtime](https://github.com/Insality/panthera)**
 
 ```
-https://github.com/Insality/panthera/archive/refs/tags/runtime.5.zip
+https://github.com/Insality/panthera/archive/refs/tags/runtime.6.zip
 ```
 
 After that, select `Project ▸ Fetch Libraries` to update [library dependencies]((https://defold.com/manuals/libraries/#setting-up-library-dependencies)). This happens automatically whenever you open a project so you will only need to do this if the dependencies change without re-opening the project.