Update changelog for release 8 (#4548)

* update changelog before release 8

Author: Ruo-Ping (Rachel) Dong

com.unity.ml-agents/CHANGELOG.md

@@ -7,32 +7,53 @@ and this project adheres to
 [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+
+### Major Changes
+#### com.unity.ml-agents (C#)
+#### ml-agents / ml-agents-envs / gym-unity (Python)
+
+### Minor Changes
+#### com.unity.ml-agents (C#)
+#### ml-agents / ml-agents-envs / gym-unity (Python)
+
+### Bug Fixes
+#### com.unity.ml-agents (C#)
+#### ml-agents / ml-agents-envs / gym-unity (Python)
+
+
+## [1.5.0-preview] - 2020-10-14
 ### Major Changes
 #### com.unity.ml-agents (C#)
 #### ml-agents / ml-agents-envs / gym-unity (Python)
  - Added the Random Network Distillation (RND) intrinsic reward signal to the Pytorch
  trainers. To use RND, add a `rnd` section to the `reward_signals` section of your
- yaml configuration file. [More information here](https://github.com/Unity-Technologies/ml-agents/blob/master/docs/Training-Configuration-File.md#rnd-intrinsic-reward)
+ yaml configuration file. [More information here](https://github.com/Unity-Technologies/ml-agents/blob/master/docs/Training-Configuration-File.md#rnd-intrinsic-reward) (#4473)
 ### Minor Changes
 #### com.unity.ml-agents (C#)
- - Stacking for compressed observations is now supported. An addtional setting
+ - Stacking for compressed observations is now supported. An additional setting
  option `Observation Stacks` is added in editor to sensor components that support
  compressed observations. A new class `ISparseChannelSensor` with an
  additional method `GetCompressedChannelMapping()`is added to generate a mapping
  of the channels in compressed data to the actual channel after decompression,
  for the python side to decompress correctly. (#4476)
- - Added new visual 3DBall environment. (#4513)
+ - Added a new visual 3DBall environment. (#4513)
 #### ml-agents / ml-agents-envs / gym-unity (Python)
  - The Communication API was changed to 1.2.0 to indicate support for stacked
  compressed observation. A new entry `compressed_channel_mapping` is added to the
  proto to handle decompression correctly. Newer versions of the package that wish to
  make use of this will also need a compatible version of the Python trainers. (#4476)
- - In `VisualFoodCollector` scene, a vector flag representing the frozen state of
+ - In the `VisualFoodCollector` scene, a vector flag representing the frozen state of
  the agent is added to the input observations in addition to the original first-person
  camera frame. The scene is able to train with the provided default config file. (#4511)
+ - Added conversion to string for sampler classes to increase the verbosity of
+ the curriculum lesson changes. The lesson updates would now output the sampler
+ stats in addition to the lesson and parameter name to the console.  (#4484)
+ - Localized documentation in Russian is added. Thanks to @SergeyMatrosov for
+ the contribution. (#4529)
 ### Bug Fixes
 #### com.unity.ml-agents (C#)
- - Fixed a bug where accessing the Academy outside of play mode would cause the Academy to get stepped multiple times when in play mode. (#4532)
+ - Fixed a bug where accessing the Academy outside of play mode would cause the
+ Academy to get stepped multiple times when in play mode. (#4532)
 #### ml-agents / ml-agents-envs / gym-unity (Python)