feat:#87 update CHANGES.md

Author: yuhaowin

CHANGES.md

@@ -7,6 +7,7 @@ Apollo Java 2.5.0
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 * [Feature Provide a new open APl to return the organization list](https://github.com/apolloconfig/apollo-java/pull/102)
+* [Feature Added a new feature to get instance count by namespace.](https://github.com/apolloconfig/apollo-java/pull/103)
 
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 All issues and pull requests are [here](https://github.com/apolloconfig/apollo-java/milestone/5?closed=1)