Update changelog

Author: merk

CHANGELOG-3.0.md

@@ -12,6 +12,10 @@ https://github.com/FriendsOfSymfony/FOSElasticaBundle/compare/v3.0.0...v3.0.1
 To generate a changelog summary since the last version, run
 `git log --no-merges --oneline v3.0.0...3.0.x`
 
+* 3.0.8 (Unreleased)
+
+ * Fixed handling of empty indexes #760
+
 * 3.0.7 (2015-01-21)
 
  * Fixed the indexing of parent/child relations, broken since 3.0 #774