Update content/en/docs/concepts/workloads/pods/sidecar-containers.md

Co-authored-by: Tim Bannister <[email protected]>

Author: PRANAV PANDEY

content/en/docs/concepts/workloads/pods/sidecar-containers.md

@@ -81,9 +81,13 @@ throughout the lifecycle of the pod and can be started and stopped independently
 main container. Unlike [init containers](/docs/concepts/workloads/pods/init-containers/),
 sidecar containers support [probes](/docs/concepts/workloads/pods/pod-lifecycle/#types-of-probe) to control their lifecycle.
 
-Sidecar containers can interact directly with the main application containers, sharing
-the same network namespace, and filesystem. They work closely together to
-provide additional functionality.
+Sidecar containers can interact directly with the main application containers, because
+like init containers they always share the same network, and can optionally also share
+volumes (filesystems).
+
+Init containers stop before the main containers start up, so init containers cannot
+exchange messages with the app container in a Pod. Any data passing is one-way
+(for example, an init container can put information inside an `emptyDir` volume).
 
 ## Resource sharing within containers