grammar: simplify

from app.grammarly.com

content/en/docs/concepts/extend-kubernetes/api-extension/custom-resources.md

@@ -44,7 +44,7 @@ The controller interprets the structured data as a record of the user's
 desired state, and continually maintains this state.
 
 You can deploy and update a custom controller on a running cluster, independently
-of the cluster's own lifecycle. Custom controllers can work with any kind of resource,
+of the cluster's lifecycle. Custom controllers can work with any kind of resource,
 but they are especially effective when combined with custom resources. The
 [Operator pattern](https://coreos.com/blog/introducing-operators.html) combines custom
 resources and custom controllers. You can use custom controllers to encode domain knowledge