Add successful response and response headers to HEAD doc

Author: chkn

api-reference/v2/tables/head-table-rows.mdx

@@ -9,4 +9,12 @@ This endpoint may be polled to detect changes in the table's data.
 
 <Tip>
   To learn more about versioning and how to detect changes, please see our guide on [data versioning](/api-reference/v2/tables/versioning).
-</Tip>
+</Tip>
+
+---
+
+#### Response Headers
+
+<ResponseField name="ETag" type="string">
+The current version of the table data.
+</ResponseField>

openapi/swagger.json

@@ -908,6 +908,18 @@
     "/tables/{tableID}/rows": {
       "head": {
         "responses": {
+          "200": {
+            "description": "",
+            "headers": {
+              "ETag": {
+                "schema": {
+                  "type": "string",
+                  "description": "The current version of the table"
+                },
+                "required": true
+              }
+            }
+          },
           "400": {
             "description": "",
             "content": {