message: fix: apiKeyValue typo in README.md
diff: @@ -83,7 +83,7 @@ $ curl -w '\n' "$(pulumi stack output swagger-url)"
  "uuid": ...
  }
  -$ curl -w '\n' -H "x-api-key: $(pulumi stack output apiKeyValue --show-secrets)" "$(pulumi stack output url)key-authorized"
  +$ curl -w '\n' -H "x-api-key: $(pulumi stack output api-key-value --show-secrets)" "$(pulumi stack output url)key-authorized"
  Hello, API Gateway!
  ```
  