Clarify entity.json vs practice.json docs, including per-practice path overrides

Practice.json already supported overriding insurance_path/pdf_path/patient_path
via Merge-Config, but the README and example only mentioned login overrides —
document that practices can have different folder paths, not just credentials.

Entities/EXAMPLE/Export1/PRACTICE_NAME/practice.json

@@ -1,13 +1,16 @@
 {
-  "_comment": "Only create this file if this practice has its own FTP login. Delete any section you don't need to override.",
+  "_comment": "Only create this file if this practice needs something different from entity.json. Delete any line/section you don't need to override — only what's listed here gets changed, everything else still comes from entity.json.",
 
   "ftps": {
     "username": "practice-specific-username",
-    "password": "practice-specific-password"
+    "password": "practice-specific-password",
+    "insurance_path": "/{practice}/CustomInsuranceFolder",
+    "pdf_path": "/{practice}/CustomPdfFolder"
   },
 
   "sftp": {
     "username": "practice-specific-username",
-    "password": "practice-specific-password"
+    "password": "practice-specific-password",
+    "patient_path": "/{practice}/CustomPatientFolder"
   }
 }