inventory.decorator: define extended manufacturing fields

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Iaf65461133bfdd335922191fda01f84d999cc8ed
diff --git a/xyz/openbmc_project/Inventory/Decorator/ManufacturerExt.interface.yaml b/xyz/openbmc_project/Inventory/Decorator/ManufacturerExt.interface.yaml
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index 0000000..42a42f2
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+description: >
+    Implement to define extended manufacturing data for inventory items.
+
+properties:
+    - name: ExtendedMFGData
+      type: dict[string, string]
+      description: >
+          A dictionary of manufacturer-specific extended data fields, which
+          may contain fields such as manufacturing plant, lot number, etc.
+
+          These fields must not be used for programatic interrogation of
+          an inventory object but may be useful for various human-oriented
+          tasks, such as part failure analysis.  Any field needed for
+          programmatic interrogation should be promoted to a first-class
+          property in another Item or Decorator interface.