Docs: Improve Color Management guide. (#25452)

* Docs: Improve Color Management guide.

* Docs: Clean up.

docs/manual/en/introduction/Color-management.html

@@ -242,6 +242,11 @@ renderer.outputEncoding = THREE.sRGBEncoding; // optional with post-processing
 		</p>
 	</blockquote>
 
+	<p>
+		Custom materials based on [page:ShaderMaterial] and [page:RawShaderMaterial] have to implement their own output color space conversion.
+		For instances of `ShaderMaterial`, adding the `encodings_fragment` shader chunk to the fragment shader's `main()` function should be sufficient.
+	</p>
+
 	<h2>Working with THREE.Color instances</h2>
 
 	<p>

docs/manual/fr/introduction/Color-management.html

@@ -242,6 +242,11 @@ renderer.outputEncoding = THREE.sRGBEncoding; // optional with post-processing
 		</p>
 	</blockquote>
 
+	<p>
+		Custom materials based on [page:ShaderMaterial] and [page:RawShaderMaterial] have to implement their own output color space conversion.
+		For instances of `ShaderMaterial`, adding the `encodings_fragment` shader chunk to the fragment shader's `main()` function should be sufficient.
+	</p>
+
 	<h2>Utiliser des instances de THREE.Color</h2>
 
 	<p>

docs/manual/it/introduction/Color-management.html

@@ -297,6 +297,11 @@
 			</p>
 		</blockquote>
 
+		<p>
+			Custom materials based on [page:ShaderMaterial] and [page:RawShaderMaterial] have to implement their own output color space conversion.
+			For instances of `ShaderMaterial`, adding the `encodings_fragment` shader chunk to the fragment shader's `main()` function should be sufficient.
+		</p>
+
 		<h2>Lavorare con le istanze di THREE.Color</h2>
 
 		<p>

docs/manual/pt-br/introduction/Color-management.html

@@ -243,6 +243,11 @@ renderer.outputEncoding = THREE.sRGBEncoding; // optional with post-processing
 		</p>
 	</blockquote>
 
+	<p>
+		Custom materials based on [page:ShaderMaterial] and [page:RawShaderMaterial] have to implement their own output color space conversion.
+		For instances of `ShaderMaterial`, adding the `encodings_fragment` shader chunk to the fragment shader's `main()` function should be sufficient.
+	</p>
+
 	<h2>Trabalhando com instâncias THREE.Color</h2>
 
 	<p>