Refactor environment variable section in values.yaml

Updated the formatting of the `env` section in the
`charts/paperless-ngx/values.yaml` file for improved clarity.
The changes include reformatting the environment variables
under the `env` key, placing them in a more readable structure
while maintaining the same functionality. This adjustment
enhances consistency across the configuration file, aiding
in better comprehension and maintenance. No breaking changes
were introduced, and the existing values remain unchanged.

charts/paperless-ngx/values.yaml

@@ -19,7 +19,7 @@ controllers:
         tag: 2.20.0
         # -- Environment variables [[ref]](https://docs.paperless-ngx.com/configuration/)
         # @default -- See [values.yaml](./values.yaml)
-      env:
+env:
   # -- Set the container timezone
   TZ: UTC
   # PAPERLESS_SECRET_KEY: ""