Remove envify, make proxy booting work with env files

lib/kamal/configuration/docs/env.yml

@@ -24,14 +24,12 @@ env:
 # KAMAL_REGISTRY_PASSWORD=pw
 # DB_PASSWORD=secret123
 # ```
-# See https://kamal-deploy.org/docs/commands/envify/ for how to use generated .env files.
 #
 # To pass the secrets you should list them under the `secret` key. When you do this the
 # other variables need to be moved under the `clear` key.
 #
 # Unlike clear values, secrets are not passed directly to the container,
 # but are stored in an env file on the host
-# The file is not updated when deploying, only when running `kamal envify` or `kamal env push`.
 env:
   clear:
     DB_USER: app