more information rfc link results in 404

`ember-optional-features@1.0.0` shows the following for further information. The [rendered](https://github.com/emberjs/rfcs/blob/async-observers/text/0494-async-observers.md) rfc link however ends up in a 404:

```
default-async-observers (Default: false)
Makes all observers asynchronous (unless manually indicated as synchronous when calling addObserver/observes).
More information: https://github.com/emberjs/rfcs/pull/494
```
Should we change the rfc link to the archive (assuming this is the official archive - just found the link through google)?
https://emberjs.github.io/rfcs/0494-async-observers.html