add: .env.example

src/server/.env.example

@@ -7,6 +7,7 @@ DB_PASSWORD=
 # On WSL find it using `hostname -I` command
 SPA_CLIENT_BASE_URL=
 SOAP_SERVICE_BASE_URL=
+REST_SERVICE_BASE_URL=
 
 # Max. 64-bit string hashed w/ bcrypt
 # Generate here: https://generate-random.org/api-key-generator?count=1&length=64&type=mixed-numbers&prefix=