add hash field to extras schema and user guide

api/schemas/extras.yaml

@@ -78,6 +78,8 @@ $defs:
         properties:
           config:
             type: string
+          hash:
+            type: string
           image_size:
             type: number
           inversions:

docs/user-guide.md

@@ -1167,6 +1167,8 @@ some common configurations in a server context.
         - pt
         - pth
         - safetensors
+    - hash
+      - string
     - image_size
       - number
     - inversions