fix

docs/vault-psql-dynamic.md

@@ -13,7 +13,7 @@ vault write psql/config/test-psql \
     plugin_name=postgresql-database-plugin \
     allowed_roles="db1-role" \
     connection_url="postgresql://{{username}}:{{password}}@psql:5432/testdb1?sslmode=disable" \
-    username="root" \
+    username="testuser" \
     password="pa$$w0rd"
 ```