docs(readme): add secrets file format information

1 files changed, 3 insertions, 0 deletions

diff --git a/README.md b/README.md
index 920b65a..dd50c87 100644
--- a/README.md
+++ b/README.md
@@ -35,6 +35,9 @@ attribute set.
 
   # Alternatively, you can use the `authUserPassFile` attribute if you are using
   # a Nix secrets manager. Here's an example using sops-nix.
+  #
+  # The secret you provide to `authUserPassFile` should be a multiline string with
+  # a single username on the first line a single password on the second line.
   services.pia.authUserPassFile = config.sops.secrets.pia.path;
 }
 ```