message: fix wrong path in readme
diff: @@ -82,7 +82,7 @@ You can obtain this information from the "Settings" tab of the server page in th
  Alternatively, you can check the 'access.txt' file under the '/opt/outline' directory of an Outline server. An example apiUrl is: https://1.2.3.4:1234/3pQ4jf6qSr5WVeMO0XOo4z.
  See [Full API Documentation](https://redocly.github.io/redoc/?url=https://raw.githubusercontent.com/Jigsaw-Code/outline-server/master/src/shadowbox/server/api.yml).
  -The OpenAPI specification can be found at [api.yml](./api.yml).
  +The OpenAPI specification can be found at [api.yml](./server/api.yml).
  ### Examples
  