Added changelog entry for r2d2

Author: mitsuhiko

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## [Unreleased](https://github.com/mitsuhiko/redis-rs/compare/0.15.0...HEAD) - ReleaseDate
+
+**Fixes and improvements**
+
+* Fixed the `r2d2` feature (re-added it) ([#265])(https://github.com/mitsuhiko/redis-rs/pull/265)
+
 ## [0.15.0](https://github.com/mitsuhiko/redis-rs/compare/0.14.0...0.15.0) - 2020-01-15
 
 **Fixes and improvements**