improve api documentation structure

Author: toshas

docs/source/en/api/pipelines/marigold.md

@@ -104,26 +104,28 @@ This ensures high-quality predictions when invoking the pipeline with only the `
 
 See also Marigold [usage examples](../../using-diffusers/marigold_usage).
 
-## MarigoldDepthPipeline
+## Marigold Depth Prediction API
+
 [[autodoc]] MarigoldDepthPipeline
-	- all
 	- __call__
 
-## MarigoldNormalsPipeline
+[[autodoc]] pipelines.marigold.pipeline_marigold_depth.MarigoldDepthOutput
+
+[[autodoc]] pipelines.marigold.marigold_image_processing.MarigoldImageProcessor.visualize_depth
+
+## Marigold Normals Estimation API
 [[autodoc]] MarigoldNormalsPipeline
-	- all
 	- __call__
 
-## MarigoldIntrinsicsPipeline
+[[autodoc]] pipelines.marigold.pipeline_marigold_normals.MarigoldNormalsOutput
+
+[[autodoc]] pipelines.marigold.marigold_image_processing.MarigoldImageProcessor.visualize_normals
+
+## Marigold Intrinsic Image Decomposition API
+
 [[autodoc]] MarigoldIntrinsicsPipeline
-	- all
 	- __call__
 
-## MarigoldDepthOutput
-[[autodoc]] pipelines.marigold.pipeline_marigold_depth.MarigoldDepthOutput
-
-## MarigoldNormalsOutput
-[[autodoc]] pipelines.marigold.pipeline_marigold_normals.MarigoldNormalsOutput
+[[autodoc]] pipelines.marigold.pipeline_marigold_intrinsics.MarigoldIntrinsicsOutput
 
-## MarigoldIntrinsicsOutput
-[[autodoc]] pipelines.marigold.pipeline_marigold_intrinsics.MarigoldIntrinsicsOutput
+[[autodoc]] pipelines.marigold.marigold_image_processing.MarigoldImageProcessor.visualize_intrinsics