the retainKeys strategy only works in the strategic merge patch

Signed-off-by: Iceber Gu <[email protected]>

Author: Iceber

content/en/docs/tasks/manage-kubernetes-objects/update-api-object-kubectl-patch.md

@@ -304,7 +304,7 @@ spec:
 Patch your Deployment:
 
 ```shell
-kubectl patch deployment retainkeys-demo --type merge --patch-file patch-file-no-retainkeys.yaml
+kubectl patch deployment retainkeys-demo --type strategic --patch-file patch-file-no-retainkeys.yaml
 ```
 
 In the output, you can see that it is not possible to set `type` as `Recreate` when a value is defined for `spec.strategy.rollingUpdate`:
@@ -330,7 +330,7 @@ With this patch, we indicate that we want to retain only the `type` key of the `
 Patch your Deployment again with this new patch:
 
 ```shell
-kubectl patch deployment retainkeys-demo --type merge --patch-file patch-file-retainkeys.yaml
+kubectl patch deployment retainkeys-demo --type strategic --patch-file patch-file-retainkeys.yaml
 ```
 
 Examine the content of the Deployment: