[Feature] DensifyReward postproc

ghstack-source-id: ef6a0f52601642c8944f63f9e3ac9e963425734e
Pull Request resolved: #2823

Author: vmoens

docs/source/reference/data.rst

@@ -1147,16 +1147,17 @@ Utils
     :toctree: generated/
     :template: rl_template.rst
 
-    MultiStep
-    consolidate_spec
-    check_no_exclusive_keys
-    contains_lazy_spec
-    Nested2TED
+    DensifyReward
     Flat2TED
     H5Combine
     H5Split
+    MultiStep
+    Nested2TED
     TED2Flat
     TED2Nested
+    check_no_exclusive_keys
+    consolidate_spec
+    contains_lazy_spec
 
 .. currentmodule:: torchrl.envs.transforms.rb_transforms