The setting became PRO_TACTS_DATA_DIR when the contacts dir moved under a
data root; nothing has read PRO_TACTS_CONTACTS_DIR since.

Assisted-by: Claude Opus 5 via Claude Code

diff --git a/README.md b/README.md
index 05dd052..3ba57c9 100644
--- a/README.md
+++ b/README.md
@@ -18,7 +18,7 @@ A CardDAV server for my family.
 ## Status
 
 Read-only and serving real data. Contacts live as KDL files under
-`data/contacts` (override with `PRO_TACTS_CONTACTS_DIR`), one contact per
+`data/contacts` (override the root with `PRO_TACTS_DATA_DIR`), one contact per
 file, the filename doubling as the contact ID and the vCard UID:
 
 ```kdl