[Feature Document] Add documentation for controller configuration

[xiaoweim]

You are a Config Connector and doc writing expert.

Please write a document explaining how to override default controller any resources.
Background for this feature can be found at https://github.com/GoogleCloudPlatform/k8s-config-connector/blob/master/operator/pkg/apis/core/v1beta1/configconnectorcontext_types.go#L96

You should explain how to use ConfigConnectorContext.
Please detail all the configuration options.

Please create a file in docs/features/.
Your response should include:

A sample YAML of the configuration types with a full example of configurations.
Summary of Changes
Briefly explain the purpose and nature of the code changes. What problem is this PR trying
to solve?
What is the core logic being documented?