Add description about custom profile

content/en/docs/tasks/debug/debug-application/debug-running-pod.md

@@ -718,3 +718,71 @@ Clean up the Pod when you're finished with it:
 ```shell
 kubectl delete pod myapp
 ```
+
+### Custom Profile {#custom-profile}
+
+{{< feature-state for_k8s_version="v1.31" state="beta" >}}
+
+You can define a partial container spec as a custom profile in either YAML or JSON format.
+The custom profile can be applied to an ephemeral container or a debugging container in a copied Pod 
+or a debugging Pod using the `--custom` flag.
+
+{{< note >}}
+Custom profile only supports the modification of the ephemeral container or debugging container spec.
+It does not support the modification of the Pod spec.
+Modifications for `command`, `image`, `lifecycle`, `name` and `volumeDevices` fields 
+via a custom profile are not allowed.
+{{< /note >}}
+
+Create a Pod named myapp as an example:
+
+```shell
+kubectl run myapp --image=busybox:1.28 --restart=Never -- sleep 1d
+```
+
+Create a custom profile in YAML or JSON format.
+Here, create a YAML format file named `custom-profile.yaml`:
+
+```yaml
+env:
+- name: ENV_VAR_1
+  value: value_1
+- name: ENV_VAR_2
+  value: value_2
+securityContext:
+  capabilities:
+    add:
+    - NET_ADMIN
+    - SYS_TIME
+
+```
+
+Run this command to debug the Pod using an ephemeral container with the custom profile:
+
+```shell
+kubectl debug -it myapp --image=busybox:1.28 --target=myapp --profile=general --custom=custom-profile.yaml
+```
+
+You can check that the ephemeral container has been added to the target Pod with the custom profile applied:
+
+```shell
+kubectl get pod myapp -o jsonpath='{.spec.ephemeralContainers[0].env}'
+```
+
+```
+[{"name":"ENV_VAR_1","value":"value_1"},{"name":"ENV_VAR_2","value":"value_2"}]
+```
+
+```shell
+kubectl get pod myapp -o jsonpath='{.spec.ephemeralContainers[0].securityContext}'
+```
+
+```
+{"capabilities":{"add":["NET_ADMIN","SYS_TIME"]}}
+```
+
+Clean up the Pod when you're finished with it:
+
+```shell
+kubectl delete pod myapp
+```