Update changelog

Don't forget to update the changelog when doing a new release.
Otherwise the changelog link in f-droid does not show you the features for the new release.

CHANGELOG.md

@@ -1,3 +1,9 @@
-## 1.0.0 (June 2016)
+## 1.0.1 (June 20, 2016)
 
-- initial release of the Nextcloud Android app 
+- Fix thumbnail preview support for new files
+- Add support for animated GIFs
+- Optimized uploader layout
+
+## 1.0.0 (June 12, 2016)
+
+- initial release of the Nextcloud Android app