Dump Entry: Recommend implementing DeleteAll

State in the description that the dump object manager should implement
xyz.openbmc_project.Collection.DeleteAll

Change-Id: I0acda3dc0bd61eb3780ed03152521da772c95983
Signed-off-by: Claire Weinan <cweinan@google.com>
diff --git a/yaml/xyz/openbmc_project/Dump/Entry.interface.yaml b/yaml/xyz/openbmc_project/Dump/Entry.interface.yaml
index 075fe1c..a6de741 100644
--- a/yaml/xyz/openbmc_project/Dump/Entry.interface.yaml
+++ b/yaml/xyz/openbmc_project/Dump/Entry.interface.yaml
@@ -6,7 +6,8 @@
     creation time.
     Object which implements this interface should implement
     xyz.openbmc_project.Object.Delete to allow the deletion of
-    individual Dump objects.
+    individual Dump objects (and its dump object manager should
+    implement xyz.openbmc_project.Collection.DeleteAll).
 
 methods:
     - name: InitiateOffload