update to add line nums for consistency with classic API section

tyk-docs/content/product-stack/tyk-gateway/middleware/circuit-breaker-tyk-classic.md

@@ -76,7 +76,7 @@ The Dashboard supports the separate `BreakerTripped` and `BreakerReset` events,
 
 The example API Definition below configures an API to listen on path `/httpbin-timeout-breaker` and forwards requests upstream to http://httpbin.org. A hard timeout value of 2 seconds is configured for path `/delay/{delay_seconds}`. This will return a `504 Gateway Timeout` response to the client if the upstream response is not received before expiry of the timer.
 
-```yaml
+```yaml {linenos=true, linenostart=1}
 apiVersion: tyk.tyk.io/v1alpha1
 kind: ApiDefinition
 metadata: