feat: Ch04 Sampling

Change-Id: I213e2d7aae2bfd75afbcd7608da9f5192df12c76
diff --git a/dcs/frames/groups.py b/dcs/frames/groups.py
index a7e2f4d..91bdd37 100644
--- a/dcs/frames/groups.py
+++ b/dcs/frames/groups.py
@@ -13,3 +13,7 @@
 
 class Ch03Group(Group):
     NAME = 'Chapter 03'
+
+
+class Ch04Group(Group):
+    NAME = 'Chapter 04'