inventory: sensors: Document related inventory association

This change just adds the associations that are already
documented here to the YAML:
https://github.com/openbmc/docs/blob/master/architecture/sensor-architecture.md#association-type-2-linking-a-low-level-hardware-item-to-its-sensors

Change-Id: I4dd23e842a6dd7e702f372efd0f192d28bfbf13b
Signed-off-by: Shounak Mitra <shounak@google.com>
diff --git a/yaml/xyz/openbmc_project/Inventory/Item.interface.yaml b/yaml/xyz/openbmc_project/Inventory/Item.interface.yaml
index d5cab89..73172cf 100644
--- a/yaml/xyz/openbmc_project/Inventory/Item.interface.yaml
+++ b/yaml/xyz/openbmc_project/Inventory/Item.interface.yaml
@@ -15,3 +15,13 @@
       type: boolean
       description: >
           Whether or not the item is present.
+
+associations:
+    - name: sensors
+      description: >
+          Sensors may implement an 'inventory' to 'sensors' association with
+          the inventory item related to it.
+      reverse_names:
+          - inventory
+      required_endpoint_interfaces:
+          - xyz.openbmc_project.Sensor.Value
\ No newline at end of file
diff --git a/yaml/xyz/openbmc_project/Sensor/Value.interface.yaml b/yaml/xyz/openbmc_project/Sensor/Value.interface.yaml
index fcfd47e..77cef58 100644
--- a/yaml/xyz/openbmc_project/Sensor/Value.interface.yaml
+++ b/yaml/xyz/openbmc_project/Sensor/Value.interface.yaml
@@ -90,3 +90,13 @@
           - name: Watts
             description: >
                 Rate of energy transfer as Watts.
+
+associations:
+    - name: inventory
+      description: >
+          Sensors may implement an 'inventory' to 'sensors' association with
+          the inventory item related to it.
+      reverse_names:
+          - sensors
+      required_endpoint_interfaces:
+          - xyz.openbmc_project.Inventory.Item
\ No newline at end of file