Add documentation for CRI API moving to v1beta1

Signed-off-by: Mrunal Patel <[email protected]>

content/en/docs/concepts/containers/container-runtime-interface.md

@@ -0,0 +1,25 @@
+
+---
+reviewers:
+- dchen1107
+- derekwaynecarr
+title: Container Runtime Interface
+content_type: concept
+weight: 20
+---
+
+<!-- overview -->
+
+{{< feature-state for_k8s_version="v1.20" state="beta" >}}
+
+This page describes the Container Runtime Interface (CRI).
+
+kubelet communicates with a container runtime such as docker, containerd or CRI-O over the CRI
+API. CRI is a grpc API with kubelet as the client and a container runtime implmenting the
+server side.
+
+CRI consists of an image service and a runtime service.
+
+The runtime service is for managing pods and containers. 
+
+The image service is concerned with managing images for containers.