Add keywords to shader stripping page [backport from DOCG-848]

com.unity.render-pipelines.universal/Documentation~/shader-stripping.md

@@ -31,17 +31,43 @@ Unity includes the following URP Assets in your build:
 - The URP Asset you set as the default render pipeline asset in [Graphics Settings](https://docs.unity3d.com/Manual/class-GraphicsSettings.html).
 - Any URP Asset you set as a **Render Pipeline Asset** in a [Quality Settings level](https://docs.unity3d.com/Manual/class-QualitySettings.html) - even if you disable the level for the current build target.
 
-| **Feature** | **How to disable the feature** |
-| :-- | :-- |
-| Additional lights | You can't strip the variants for this feature. |
-| Ambient occlusion | Remove the [**Ambient Occlusion**](post-processing-ssao.md) Renderer Feature in all Renderers that URP Assets use. |
-| Decals | Remove the [**Decals**](renderer-feature-decal.md) Renderer Feature in all Renderers that URP Assets use. |
-| Reflection Probe blending | Disable [**Probe Blending**](lighting/reflection-probes.md). |
-| Reflection Probe box projection | Disable [**Box Projection**](lighting/reflection-probes.md). |
-| Render Pass | Disable **Native Render** in all Renderers that URP Assets use. |
-| Light Layers | Disable [**Light Layers**](features/light-layers.md). |
-| Shadows from additional lights | You can't strip the variants for this feature. |
-| Shadows from the main light | You can't strip the variants for this feature. |
+Avoid including URP Assets in your build that use different [rendering paths](urp-universal-renderer.html#rendering-path-comparison) because this causes Unity to create two sets of variants for each keyword.
+
+| **Feature** | **How to disable the feature** | **Shader keywords this turns off** | **Rendering Path** |
+| - | - | - | - |
+| Accurate G-buffer normals | Disable **Accurate G-buffer normals** in the URP Asset. This has no effect on platforms that use the Vulkan graphics API. | `_GBUFFER_NORMALS_OCT` | Deferred |
+| Additional lights | In the **URP Asset**, in the **Lighting section**, disable **Additional Lights**. | `_ADDITIONAL_LIGHTS`, `_ADDITIONAL_LIGHTS_VERTEX` | Forward |
+| Ambient occlusion | Remove the [Ambient Occlusion](post-processing-ssao.html) Renderer Feature in all Renderers that URP Assets use. | `_SCREEN_SPACE_OCCLUSION` | Forward and Deferred |
+| Decals | Remove the [Decals](renderer-feature-decal.html) Renderer Feature in all Renderers that URP Assets use. |  `_DBUFFER_MRT1`, `_DBUFFER_MRT2`, `_DBUFFER_MRT3`, `_DECAL_NORMAL_BLEND_LOW`, `_DECAL_NORMAL_BLEND_MEDIUM`, `_DECAL_NORMAL_BLEND_HIGH`,  `_DECAL_LAYERS` | Forward and Deferred |
+| Fast sRGB to linear conversion | In the **URP Asset**, in the **Post-processing** section, disable **Fast sRGB/Linear conversions**. | `_USE_FAST_SRGB_LINEAR_CONVERSION` | Forward and Deferred |
+| Holes in terrain | In the **URP Asset**, in the **Rendering** section, disable **Terrain Holes**. | `_ALPHATEST_ON` | Forward |
+| Light cookies | Remove [Cookie textures](https://docs.unity3d.com/Manual/Cookies.html) from all the lights in your project. | `_LIGHT_COOKIES` | Forward and Deferred |
+| Light layers | Disable [Light Layers](features/light-layers.md). | `_LIGHT_LAYERS` | Forward and Deferred |
+| Reflection Probe blending | Disable [Probe Blending](lighting/reflection-probes.html#configuring-reflection-probe-settings). | `_REFLECTION_PROBE_BLENDING` | Forward and Deferred |
+| Reflection Probe box projection | Disable [Box Projection](lighting/reflection-probes.html#configuring-reflection-probe-settings). | `_REFLECTION_PROBE_BOX_PROJECTION` | Forward and Deferred |
+| Render Pass | Disable **Native Render** in all Renderers that URP Assets use. | `_RENDER_PASS_ENABLED` | Forward and Deferred |
+| Shadows from additional lights | In the URP Asset, in the **Additional Lights** section, disable **Cast Shadows**. | `_ADDITIONAL_LIGHT_SHADOWS` | Forward and Deferred |
+| Shadows from the main light | In the URP Asset, in the **Main Light** section, disable **Cast Shadows**. The keywords Unity removes might depend on your settings. | `_MAIN_LIGHT_SHADOWS`, `_MAIN_LIGHT_SHADOWS_CASCADE`, `_MAIN_LIGHT_SHADOWS_SCREEN` | Forward and Deferred |
+| Soft shadows | In the URP Asset, in the **Shadows** section, disable **Soft shadows**. | `_SHADOWS_SOFT` | Forward and Deferred |
+
+## Strip post-processing shader variants
+
+Enable **Strip Unused Post Processing Variants** in [URP Global Settings](urp-global-settings.md) to strip shader variants for [Volume Overrides](VolumeOverrides.md) you don't use.
+
+For example if your project uses only the Bloom effect, URP keeps Bloom variants but strips all other post-processing variants.
+
+Unity checks for Volume Overrides in all scenes, so you can't strip variants by removing a Scene from your build but keeping it in your project.
+
+| **Volume Override removed** | **Shader keywords this turns off** |
+| - | - |
+| Bloom | `_BLOOM_HQ`, `BLOOM_HQ_DIRT`, `_BLOOM_LQ`, `BLOOM_LQ_DIRT` |
+| Chromatic Aberration | `_CHROMATIC_ABERRATION` |
+| Film Grain | `_FILM_GRAIN` |
+| HDR Grading | `_HDR_GRADING` |
+| Lens Distortion | `_DISTORTION` |
+| Tonemapping | `_TONEMAP_ACES`, `_TONEMAP_NEUTRAL`, `_TONEMAP_GRADING` |
+
+You should also enable **Strip Screen Coord Override Variants** in URP Global Settings, unless you override screen coordinates to support post processing on large numbers of multiple displays ('cluster' displays).
 
 ## Strip XR and VR shader variants