Documentation and images for custom mip for texture samplers (#6592)

* Documentation and images for custom mip for texture samplers

* Code review suggested changes.

Author: kecho

com.unity.render-pipelines.high-definition/Documentation~/Images/CustomMipSupportNode.png

@@ -62,6 +62,22 @@ Your Unity project now supports DLSS and you can now enable DLSS for Cameras in
 The **Use Optimal Settings** checkbox in the [HDRP Assets](HDRP-Asset.md) is enabled by default. This means that DLSS sets the dynamic resolution scale automatically.
 If you disable this checkbox DLSS uses the same dynamic resolution scale set by the project. For more information see the [Dynamic Resolution](Dynamic-Resolution.md) guide.
 
+### Mip bias in DLSS
+
+To enable automatic mip bias correction when you enable DLSS, open the [HDRP Asset](HDRP-Asset.md) and enable the **Use Mip Bias** checkbox.
+
+If you need a specific custom mip bias for a Texture, create a custom sampler that samples from TextureInput, SamplerInput, UV, and MipBias. To do this, enter the following script into the Node Settings ' Body field. The images below display this example:
+
+```glsl
+Out = SAMPLE_TEXTURE2D_BIAS(TextureInput, SamplerInput, UV, MipBias);
+```
+
+![](Images/CustomMipSupportNode.png)
+
+
+![](Images/CustomMipSupportNodeExample.png)
+
+
 ### Setting the DLSS quality mode
 
 DLSS now works in your project, but you can change the quality mode to customize DLSS towards performance or quality. You can do this on a project level or a per-Camera level. For information about the available quality modes, see [Quality modes](https://docs.unity3d.com/2021.2/Documentation/Manual/deep-learning-super-sampling.html).