Add docs for parameter store to README

README.rst

@@ -111,8 +111,16 @@ The |file-sample_env|_ file contains all the required environment variable for t
 Sample values are provided in this file but the actual values are to be included
 in the ``app/settings/.env`` file at the appropriate location.
 
-The actual values are added to ``ready-to-trade`` `vault`. Please use the values
-corresponding to the ``dev`` environment.
+The actual values are added to the `Parameter store <https://eu-west-2.console.aws.amazon.com/systems-manager/parameters?region=eu-west-2&tab=Table#>`_.
+Ensure you are in the correct AWS account when accessing the parameter store. For dev, uat and staging use the
+``datahub`` acount when accessing the `AWS account page <https://uktrade.awsapps.com/start/#/?tab=accounts>`_
+Once in the parameter store, you can filter for the ``dev`` environment.
+
+.. admonition:: Gov PaaS will be deprecated from July 2024 and keys will be moved from Vault to Parameter Store.
+   :class: warning
+
+   The actual values are added to ``ready-to-trade`` `vault`. Please use the values
+   corresponding to the ``dev`` environment.
 
 Single Sign On (SSO)
 ^^^^^^^^^^^^^^^^^^^^