Add removal of environment variable to make it default

Author: ardaguclu

keps/sig-cli/3638-kubectl-plugin-subcommands/README.md

@@ -273,11 +273,12 @@ in back-to-back releases.
 #### Beta
 
 - Gather feedback from developers and surveys
+- Add integration tests
+- Remove `KUBECTL_ENABLE_CMD_SHADOW` environment variable and this feature will be enabled by default.
 
 #### GA
 
 - Add e2e test
-- Add integration tests
 - Enable shadowing for all non-existent subcommands
 
 ### Upgrade / Downgrade Strategy
@@ -668,6 +669,7 @@ For each of them, fill in the following information by copying the below templat
 
 ## Implementation History
 The KEP was proposed on 2022-10-22
+The KEP was promoted to beta on 2023-10-02
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