docs: clarify host path mapping and volume configuration

.env.example

@@ -1,7 +1,16 @@
 # Obsidian Sync Configuration
+
+# 1. Remote Vault Details
 OBSIDIAN_VAULT_NAME=MyVault
 OBSIDIAN_SYNC_PASSWORD=your_encryption_password_here
 OBSIDIAN_DEVICE_NAME=Docker-Sync-Server
+
+# 2. Local Filesystem Mapping
+# IMPORTANT: Use an ABSOLUTE PATH here.
+# This is where your notes will be stored on your actual computer/server.
+# Example: /home/travis/my-obsidian-vault
+VAULT_HOST_PATH=/path/to/your/local/vault
+
+# 3. Authentication
+# Leave blank if you prefer to run 'docker exec -it obsidian-sync-server ob login'
 OBSIDIAN_SYNC_TOKEN=
-# The path on the host where the vault will be mirrored
-VAULT_HOST_PATH=./vault