Updating the Changelog and Migrating (#3620)

Author: vincentpierre

com.unity.ml-agents/CHANGELOG.md

@@ -6,6 +6,12 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 
 ## [Unreleased]
+### Major Changes
+
+### Minor Changes
+
+
+## [0.15.0-preview] - 2020-03-18
 ### Major Changes
  - `Agent.CollectObservations` now takes a VectorSensor argument. (#3352, #3389)
  - Added `Agent.CollectDiscreteActionMasks` virtual method with a `DiscreteActionMasker` argument to specify which discrete actions are unavailable to the Agent. (#3525)

docs/Migrating.md

@@ -7,7 +7,14 @@ The versions can be found in
 
 # Migrating
 
-## Migrating from 0.14 to latest
+## Migrating from 0.15 to latest
+
+### Important changes
+
+### Steps to Migrate
+
+
+## Migrating from 0.14 to 0.15
 
 ### Important changes
 * The `Agent.CollectObservations()` virtual method now takes as input a `VectorSensor` sensor as argument. The `Agent.AddVectorObs()` methods were removed.