Revert "Document the environment variable substitution feature of con…

…figMapGenerator"

This reverts commit b9da040.

content/en/docs/tasks/manage-kubernetes-objects/kustomization.md

@@ -86,20 +86,12 @@ metadata:
   name: example-configmap-1-8mbdf7882g
 ```
 
-To generate a ConfigMap from an env file, add an entry to the `envs` list in `configMapGenerator`. This can also be used to set values from local environment variables by omitting the `=` and the value.
-
-{{< note >}}
-It's recommended to use the local environment variable population functionality sparingly - an overlay with a patch is often more maintainable. Setting values from the environment may be useful when they cannot easily be predicted, such as a git SHA.
-{{< /note >}}
-
-Here is an example of generating a ConfigMap with a data item from a `.env` file:
+To generate a ConfigMap from an env file, add an entry to the `envs` list in `configMapGenerator`. Here is an example of generating a ConfigMap with a data item from a `.env` file:
 
 ```shell
 # Create a .env file
-# BAZ will be populated from the local environment variable $BAZ
 cat <<EOF >.env
 FOO=Bar
-BAZ
 EOF
 
 cat <<EOF >./kustomization.yaml
@@ -113,19 +105,18 @@ EOF
 The generated ConfigMap can be examined with the following command:
 
 ```shell
-BAZ=Qux kubectl kustomize ./
+kubectl kustomize ./
 ```
 
 The generated ConfigMap is:
 
 ```yaml
 apiVersion: v1
 data:
-  BAZ: Qux
   FOO: Bar
 kind: ConfigMap
 metadata:
-  name: example-configmap-1-892ghb99c8
+  name: example-configmap-1-42cfbf598f
 ```
 
 {{< note >}}