Add .env to shared, remove unecessary writable config

[simonrjones]

• Bug fix Craft CMS recipe issues #3584

This is to make two small changes to the Craft CMS recipe to add the .env file to shared & remove the writable config which causes issues for our own deployments. Since no other recipes add writable config I presume this is unnecessary.

Once merged in:

  Please, regenerate docs by running next command:
  $ php bin/docgen