Update changelog.md

Author: misaochan

CHANGELOG.md

@@ -1,5 +1,15 @@
 # Wikimedia Commons for Android
 
+## v2.8.0
+- Fixed failed uploads by modifying auth token 
+- Fixed crashes during upload by storing file temporarily
+- Added automatic Wikidata p18 edits upon Nearby upload
+- Added Explore feature to browse other Commons images, including featured images
+- Added Achievements feature to see current level and upload stats
+- Added quiz for users with high deletion rates
+- Added first run tutorial for Nearby
+- Various small improvements to ShareActivity UI
+
 ## v2.7.2
 - Modified subtext for "automatically get current location" setting to emphasize that it will reveal user's location