Update rest-api-spec main (#2753)

Co-authored-by: pquentin <[email protected]>
Co-authored-by: Quentin Pradet <[email protected]>

Author: github-actions[bot]

output/schema/validation-errors.json

@@ -53,6 +53,10 @@
         "options": ["open", "closed", "hidden", "none", "all"],
         "default": "open",
         "description": "Whether to expand wildcard expression to concrete indices that are open, closed or both."
+      },
+      "master_timeout": {
+        "type": "time",
+        "description": "Explicit operation timeout for connection to master node"
       }
     }
   }