prepare for release 3.4.0 (#315)

CHANGELOG.md

@@ -1,5 +1,17 @@
 # Optimizely Android X SDK Changelog
 
+## 3.4.0
+January 31st, 2020
+
+This release includes a new API to access project configuration data.
+
+### New Features
+- Added a new API to get project configuration static data.
+  - Call `getOptimizelyConfig()` to get a snapshot of project configuration static data.
+  - It returns an `OptimizelyConfig` instance which includes a datafile revision number, all experiments, and feature flags mapped by their key values.
+  - Added caching for `getOptimizelyConfig` - `OptimizelyConfig` object will be cached and reused for the lifetime of the datafile.
+  - For details, refer to our documentation page: [https://docs.developers.optimizely.com/full-stack/docs/optimizelyconfig-android](https://docs.developers.optimizely.com/full-stack/docs/optimizelyconfig-android).
+
 ## 3.3.0
 October 31st, 2019