Added documentation for Shader Graph Project Settings and related changes

Added documentation to fix [DOCATT-4884](https://jira.unity3d.com/browse/DOCATT-4884). New Shader Graph project settings and changes to Shader Graph preferences.

Author: PBU3D

Packages/com.unity.shadergraph/Documentation~/Shader-Graph-Preferences.md

@@ -1,11 +1,21 @@
 # Shader Graph Preferences
 
-To access the Shader Graph Project-wide settings, click **Edit** > **Preferences**, and then select **Shader Graph**.
+Use the Shader Graph preferences to define shader graph settings for your system. To access the Shader Graph system preferences, do the following:
+
+1. From the main menu select **Edit** > **Preferences** (macOS: **Unity** > **Settings**). The **Preferences** window is displayed. 
+2. Select **Shader Graph**.
 
 ## Settings
 
-| Name | Description |
-|:------- |:----------- |
-|Shader Variant Limit| Enter a value to set the maximum number of shader variants. If your graph exceeds this maximum value, Unity throws the following error: _Validation: Graph is generating too many variants. Either delete Keywords, reduce Keyword variants or increase the Shader Variant Limit in Preferences > Shader Graph._ For more information about shader variants, see [Making multiple shader program variants](https://docs.unity3d.com/Manual/SL-MultipleProgramVariants.html). |
-| Automatically Add or Remove Block Nodes | Toggle either on or off. If this option is on, when changing Graph Settings any needed Block nodes will be added to the Master Stack. Any incompatible Block nodes that have no incoming connections will be removed from the Master Stack. If this option is off, no Block nodes will be added to or removed from the Master Stack. |
-Enable Deprecated Nodes | Enable this setting to turn off warnings for deprecated nodes and properties, which also allows you to create older versions of nodes and properties. If you don't enable this setting, Shader Graph displays warnings for deprecated nodes and properties, and any new nodes and properties you create use the latest version. |
+| Name                      | Description                             |
+|:--------------------------|:----------------------------------------|
+| **Preview Variant Limit** | Set the maximum number of variants allowed in local projects. This is a local version of the **Shader Variant Limit** in the project settings. If your graph exceeds this maximum value, Unity returns the following error:</br> _Validation: Graph is generating too many variants. Either delete Keywords, reduce Keyword variants or increase the **Shader Variant Limit** in Preferences > Shader Graph._ </br>For more information about shader variants, refer to [Making multiple shader program variants](https://docs.unity3d.com/Manual/SL-MultipleProgramVariants.html). For more information about the Shader Variant Limit, refer to [Shader graph project settings](Shader-Graph-Project-Settings.md)|
+| **Automatically Add and Remove Block Nodes** | Automatically add [Block nodes](Block-Node.md) to, or remove them from, the [Master Stack](Master-Stack.md) as needed. If you select this option, any [Block nodes](Block-Node.md) that your Shader graph needs are added to the [Master Stack](Master-Stack.md) automatically. Any incompatible [Block nodes](Block-Node.md) that have no incoming connections will be removed from the [Master Stack](Master-Stack.md). If you don't select this option, no [Block nodes](Block-Node.md) are added to, or removed from, the [Master Stack](Master-Stack.md) automatically. |
+| **Enable Deprecated Nodes** | Disable warnings for deprecated nodes and properties. If you select this option, Shader Graph doesn't display warnings if your graph contains deprecated nodes or properties. If you don't select this option, Shader Graph displays warnings for deprecated nodes and properties, and any new nodes and properties you create use the latest version.  |
+| **Zoom Step Size**        | Control how much the camera in Shader Graph zooms each time you roll the mouse wheel. This makes it easier to control the difference in zoom speed between the touchpad and mouse. A touchpad simulates hundreds of steps, which causes very fast zooms, whereas a mouse wheel steps once with each click. |
+
+## Additional resources
+
+- [Making multiple shader program variants](https://docs.unity3d.com/Manual/SL-MultipleProgramVariants.html)
+- [Master Stack](Master-Stack.md)
+- [Shader graph project settings](Shader-Graph-Project-Settings.md)

Packages/com.unity.shadergraph/Documentation~/Shader-Graph-Project-Settings.md

@@ -0,0 +1,34 @@
+# Shader Graph project settings reference
+
+Use the Shader Graph project settings to define shader graph settings for your entire project. To access the Shader Graph project settings, do the following:
+
+1. From the main menu select **Edit** > **Project Settings**. The **Project Settings** window is displayed. 
+2. Select **ShaderGraph**.
+
+
+| Property                 | Description |
+|:-------------------------|:----------- |
+| **Shader Variant Limit** | Set the maximum number of variants allowed in the project. If your graph exceeds this maximum value, Unity returns the following error:<br/> Validation: Graph is generating too many variants. Either delete Keywords, reduce Keyword variants or increase the Shader Variant Limit in Preferences > Shader Graph. <br/>For more information about shader variants, refer to [Making multiple shader program variants](https://docs.unity3d.com/Manual/SL-MultipleProgramVariants.html). |
+
+
+## Custom Interpolator Channel Settings
+
+It's impossible to limit the number of channels users can create in a Shader Graph. Use **Custom Interpolator Channel Settings** to create alerts that let users know when they're close to, or have exceeded, the channel limit for the target platform. Unity uses these settings to help Shader Graph users maintain compatibility with target platforms when using custom interpolators. For more information, refer to [Custom interpolators](Custom-Interpolators.md).
+
+| Property                 | Description                        |
+|:-------------------------|:-----------------------------------|
+| **Error Threshold**      | Specify the number of channels at which users are notified that they're at, or have surpassed, the channel limit. This property has a minimum value of 8 channels and must be higher than **Warning Threshold**. |
+| **Warning Threshold**    | Specify the number of channels at which users are warned that they are close to the channel limit. This property must be lower than **Error Threshold** and between 8 and 32 channels. |
+
+## Heatmap Color Mode Settings 
+
+You can create multiple customized heatmap values assets and swap them in and out based on the current needs of your project. Use **Heatmap Color Mode Settings** to specify which custom heatmap values asset to use for your project. 
+
+| Property          | Description                                |
+|:------------------|:-------------------------------------------|
+| **Custom Values** | Specify which set of customized heatmap values to use for your project. |
+
+## Additional resources
+
+- [Custom interpolators](Custom-Interpolators.md)
+- [Making multiple shader program variants](https://docs.unity3d.com/Manual/SL-MultipleProgramVariants.html)

Packages/com.unity.shadergraph/Documentation~/TableOfContents.md

@@ -16,6 +16,7 @@
     * [Preview Mode Control](Preview-Mode-Control)
     * [Custom Function Node](Custom-Function-Node)
     * [Shader Graph Preferences](Shader-Graph-Preferences)
+    * [Shader Graph Project Settings](Shader-Graph-Project-Settings.md)
     * [Shader Graph Keyboard Shortcuts](Keyboard-shortcuts)
     * [Samples](ShaderGraph-Samples.md)
         * [Feature Examples](Shader-Graph-Sample-Feature-Examples.md)