docs: add beta warnings for Kubernetes native executor deployment options (#448)

closes PLAT-704

Provide a warning to admins or developers reviewing the k8s-native
executors deployment type. These changes are intended to prevent further
adoption of a deployment type that may not work with future iteractions
sourcegraph and executors

Author: DaedalusG

components/executors/dind/README.md

@@ -1,5 +1,10 @@
 # Executors (Docker-in-Docker)
 
+> ⚠️ **Beta:** Docker-in-Docker Kubernetes executors are not recommended for production use.
+> This method requires privileged access to a container runtime daemon. For production workloads,
+> deploy via [Terraform](https://docs.sourcegraph.com/self-hosted/executors/deploy-executors-terraform)
+> or [binary](https://docs.sourcegraph.com/self-hosted/executors/deploy-executors-binary).
+
 Executors are Sourcegraph’s solution for running untrusted code in a secure and controllable way. For more information on dind executors and how they are used see the Executors [dind documentation](https://docs.sourcegraph.com/admin/executors/deploy_executors_dind)
 
 ## Deploying

components/executors/k8s/README.md

@@ -1,5 +1,9 @@
 # Executors (Native Kubernetes)
 
+> ⚠️ **Beta:** Native Kubernetes executors are in beta. For production workloads, consider deploying using
+> [Terraform](https://docs.sourcegraph.com/self-hosted/executors/deploy-executors-terraform) or the
+> [Linux binary](https://docs.sourcegraph.com/self-hosted/executors/deploy-executors-binary) for better long-term support.
+
 Executors are Sourcegraph’s solution for running untrusted code in a secure and controllable way. For more information on native kubernetes executors and how they are used see the [Executors documentation](https://docs.sourcegraph.com/admin/executors/deploy_executors_kubernetes)
 
 ## Deploying

examples/executors/README.md

@@ -1,5 +1,8 @@
 # Quickstart overlay for executors
 
+> ⚠️ **Note:** This overlay deploys native Kubernetes executors, which are in beta and not
+> recommended for production use.
+
 This overlay:
 
 - deploys Sourcegraph without monitoring services