docs: clarify own refresh mechanism (#232)

README.md

@@ -296,6 +296,6 @@ If `bootstrapOverride` is `false` any local cached data will not be overridden u
 
 ## Manage your own refresh mechanism
 
-You can opt out of the Unleash feature flag auto-refresh mechanism and metrics update by settings the `refreshInterval` and/or `metricsInterval` options to `false`. 
+You can opt out of the Unleash feature flag auto-refresh mechanism and metrics update by settings the `refreshInterval` and/or `metricsInterval` options to `0`. 
 In this case, it becomes your responsibility to call `updateToggles` and/or `sendMetrics` methods.
 This approach is useful in environments that do not support the `setInterval` API, such as service workers.