fix(specs): add primary to get settings response (#3415)

Author: kai687

specs/search/common/schemas/SettingsResponse.yml

@@ -0,0 +1,13 @@
+settingsResponse:
+  allOf:
+    - $ref: '../../../common/schemas/IndexSettings.yml#/indexSettings'
+    - $ref: '#/WithPrimary'
+
+WithPrimary:
+  type: object
+  additionalProperties: false
+  properties:
+    primary:
+      type: string
+      description: |
+        Replica indices only: the name of the primary index for this replica.

specs/search/paths/settings/settings.yml

@@ -14,7 +14,7 @@ get:
       content:
         application/json:
           schema:
-            $ref: '../../../common/schemas/IndexSettings.yml#/indexSettings'
+            $ref: '../../common/schemas/SettingsResponse.yml#/settingsResponse'
     '400':
       $ref: '../../../common/responses/BadRequest.yml'
     '402':