* feat: Have githubwebhook monitor a single namespace
When using `scope.singleNamespace: true` in Helm, expected behaviour is
that the github webhook server behaves the same way as the controller.
The current behaviour is that the webhook server monitors all the
namespaces.
* Changing the chart README.md to reflect the scope
The documentation now mentions that both the controller and the github
webhook server will make use of the `scope.watchNamespace` field if
`scope.singleNamespace` is set to `true`.
Co-authored-by: Sebastien Le Digabel <sebastien.ledigabel@skyscanner.net>