Added 2.0.x release notes and updated changelog to [keep a changelog] format

com.unity.render-pipelines.lightweight/CHANGELOG.md

 # Changelog
+All notable changes to this package will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
+and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
+
+## [2.0.1-preview]
+
+### Fixed
+- VR Single Pass Instancing shadows
+
+## [2.0.0-preview]
+
+### Added
+- Explicit render target load/store actions were added to improve tile utilization
+- Camera opaque color can be requested on the pipeline asset. It can be accessed in the shader by defining a _CameraOpaqueTexture. This can be used as an alternative to GrabPass.
+- Dynamic Batching can be enabled in the pipeline asset
+- Pipeline now strips unused or invalid variants and passes based on selected pipeline capabilities in the asset. This reduces build and memory consuption on target.
+- Shader stripping settings were added to pipeline asset
+
+### Changed
+#### Pipeline
+- Pipeline code is now more modular and extensible. A ForwardRenderer class is initialized by the pipeline with RenderingData and it's responsible for enqueueing and executing passes. In the future pluggable renderers will be supported.
+- On mobile 1 directional light + up to 4 local lights (point or spot) are computed
+- On other platforms 1 directional light + up to 8 local lights are computed
+- Multiple shadow casting lights are supported. Currently only 1 directional + 4 spots light shadows.
+#### Shading Framework
+- Directional Lights are always considered a main light in shader. They have a fast shading path with no branching and no indexing.
+- GetMainLight() is provided in shader to initialize Light struct with main light shading data. 
+- Directional lights have a dedicated shadowmap for performance reasons. Shadow coord always comes from interpolator.
+- MainLigthRealtimeShadowAttenuation(float4 shadowCoord) is provided to compute main light realtime shadows.
+- Spot and Point lights are always shaded in the light loop. Branching on uniform and indexing happens when shading them.
+- GetLight(half index, float3 positionWS) is provided in shader to initialize Light struct for spot and point lights.
+- Spot light shadows are baked into a single shadow atlas.
+- Shadow coord for spot lights is always computed on fragment.
+- Use LocalLightShadowAttenuation(int lightIndex, float3 positionWS) to comppute realtime shadows for spot lights.
+
+### Fixed
+- Issue that was causing VR on Android to render black
+- Camera viewport issues
+- UWP build issues
+- Prevent nested camera rendering in the pipeline
-### Improvements
+
+### Added
- 
-### Bugfixes
- - Fixed SRP Shader library issue that was causing all constants to be highp in mobile
- - Fixed shader error that prevented LWRP to build to UWP
- - Fixed shader compilation errors in Linux due to case sensitive includes
- - Fixed Rendering Texture flipping issue
- - Fixed Standard Particles shader cutout and blending modes
- - Fixed crash caused by using projectors
- - Fixed issue that was causing Shadow Strength to not be computed on mobile
- - Fixed Material Upgrader issue that caused editor to SoftLocks
- - Fixed GI in Unlit shader
- - Fixed null reference in the Unlit material shader GUI
+
+### Fixed
+ - SRP Shader library issue that was causing all constants to be highp in mobile
+ - shader error that prevented LWRP to build to UWP
+ - shader compilation errors in Linux due to case sensitive includes
+ - Rendering Texture flipping issue
+ - Standard Particles shader cutout and blending modes
+ - crash caused by using projectors
+ - issue that was causing Shadow Strength to not be computed on mobile
+ - Material Upgrader issue that caused editor to SoftLocks
+ - GI in Unlit shader
+ - Null reference in the Unlit material shader GUI
-### Improvements
+
+### Changed
-  
-### Bugfixes
- - Fixed shadows on GLES 2.0
- - Fixed CPU performance regression in shadow rendering
- - Fixed alpha clip shadow issues
- - Fixed unmatched command buffer error message
- - Fixed null reference exception caused by missing resource in LWRP
- - Fixed issue that was causing Camera clear flags was being ignored in mobile
+
+### Fixed
+ - Shadows on GLES 2.0
+ - CPU performance regression in shadow rendering
+ - Alpha clip shadow issues
+ - Unmatched command buffer error message
+ - Null reference exception caused by missing resource in LWRP
+ - Issue that was causing Camera clear flags was being ignored in mobile
+
-### Improvements
+
+### Added
- - Shadowmap uses 16bit format instead of 32bit.
+ 
+### Changed
+ - Shadowmap uses 16bit format instead of 32bit.
-### Bugfixes
- - Fixed Subtractive Mode
+### Fixed
+ - Subtractive Mode
+ 
-### Improvements
- - Refactored lightweight standard shaders and shader library to improve ease of use.
+
+### Added
- - HDR RT now uses what format is configured in Tier settings.
- - Optimized tile LOAD op on mobile.
+ 
+### Changed
+ - HDR RT now uses what format is configured in Tier settings.
+ - Refactored lightweight standard shaders and shader library to improve ease of use.
+ - Optimized tile LOAD op on mobile.
-
-### Bugfixes
- - Fixed realtime shadows on OpenGL
- - Fixed shader compiler errors in GLES 2.0
- - Fixed issue sorting issues when BeforeTransparent custom fx was enabled.
- - Fixed VR single pass rendering.
- - Fixed viewport rendering issues when rendering to backbuffer.
- - Fixed viewport rendering issues when rendering to with MSAA turned off.
- - Fixed multi-camera rendering.
+ 
+### Fixed
+ - Realtime shadows on OpenGL
+ - Shader compiler errors in GLES 2.0
+ - Issue sorting issues when BeforeTransparent custom fx was enabled.
+ - VR single pass rendering.
+ - Viewport rendering issues when rendering to backbuffer.
+ - Viewport rendering issues when rendering to with MSAA turned off.
+ - Multi-camera rendering.
-### Improvements
- - Shaders ported to the new SRP shader library. 
- - Constant Buffer Refactor to use new Batcher
+
+### Added
+ - UI Improvements (Rendering features not supported by LW are hidden)
+
+### Changed
+ - Shaders were ported to the new SRP shader library. 
+ - Constant Buffer refactor to use new Batcher
- - UI Improvements (Rendering features not supported by LW are hidden)
- 
-### Bugfixes
+
+### Fixed
-### Improvements
- - Realtime shadow filtering was improved. 
+
+### Added
-### Bugfixes
+### Changed
+- Realtime shadow filtering was improved. 
+
+### Fixed
+
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