Api-ref: change fix `extra-spec-key` key in path

TrivialFix:
In the API Unset an extra spec:
/v2/{tenant_id}/types/{share_type_id}/extra_specs/{extra-spec-key}
the key extra-spec-key should be in path, but it is in body, this
is to fix this.

Change-Id: Ia6f01a6bca369ca4b922a45e8e6ece4f583528c7

api-ref/source/parameters.yaml

@@ -14,6 +14,12 @@ export_location_id_path:
   in: path
   required: true
   type: string
+extra-spec-key-path:
+  description: |
+    The extra specification key
+  in: path
+  required: true
+  type: string
 group_snapshot_id_path:
   description: |
     The group snapshot ID.

api-ref/source/share-types.inc

@@ -486,7 +486,7 @@ Request
 
    - tenant_id: tenant_id_path
    - share_type_id: share_type_id
-   - extra-spec-key: extra-spec-key
+   - extra-spec-key: extra-spec-key-path
 
 
 Add share type access