Clarify Rack middleware_names option

docs/GettingStarted.md

@@ -1230,7 +1230,7 @@ Where `options` is an optional `Hash` that accepts the following parameters:
 | `application` | Your Rack application. Required for `middleware_names`. | `nil` |
 | `distributed_tracing` | Enables [distributed tracing](#distributed-tracing) so that this service trace is connected with a trace of another service if tracing headers are received | `true` |
 | `headers` | Hash of HTTP request or response headers to add as tags to the `rack.request`. Accepts `request` and `response` keys with Array values e.g. `['Last-Modified']`. Adds `http.request.headers.*` and `http.response.headers.*` tags respectively. | `{ response: ['Content-Type', 'X-Request-ID'] }` |
-| `middleware_names` | Enable this if you want to use the middleware classes as the resource names for `rack` spans. Requires `application` option to use. | `false` |
+| `middleware_names` | Enable this if you want to use the last executed middleware class as the resource name for the `rack` span. If enabled alongside the `rails` instrumention, `rails` takes precedence by setting the `rack` resource name to the active `rails` controller when applicable. Requires `application` option to use. | `false` |
 | `quantize` | Hash containing options for quantization. May include `:query` or `:fragment`. | `{}` |
 | `quantize.query` | Hash containing options for query portion of URL quantization. May include `:show` or `:exclude`. See options below. Option must be nested inside the `quantize` option. | `{}` |
 | `quantize.query.show` | Defines which values should always be shown. Shows no values by default. May be an Array of strings, or `:all` to show all values. Option must be nested inside the `query` option. | `nil` |