Item, LED: add identifying association

Create association documentation between LED and Item.

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I121cd09cd3eb032400200e51a1c94e2dfcc872cc
diff --git a/yaml/xyz/openbmc_project/Led/Group.interface.yaml b/yaml/xyz/openbmc_project/Led/Group.interface.yaml
index 56caba2..adde5ec 100644
--- a/yaml/xyz/openbmc_project/Led/Group.interface.yaml
+++ b/yaml/xyz/openbmc_project/Led/Group.interface.yaml
@@ -6,3 +6,12 @@
       description: >
           Whether or not the group is currently asserted.
           To assert a group, set to True. To de-assert a group, set to False.
+
+associations:
+    - name: identifying
+      description: >
+          Objects that implement LED group can optionally implement the
+          'identifying' association to provide a link back to a Item.
+      reverse_name: identified_by
+      required_endpoint_interfaces:
+          - xyz.openbmc_project.Inventory.Item