making rest api better again

docs/post.md

@@ -18,6 +18,22 @@ Create a Parking Lot
 
 `pricing_policy` should not be null
 
+***Pricing policy data structure***
+example:
+```json  
+"pricing_policy": {
+   "type": "simple",
+   "flat_fee": 1,
+   "per_hour_fare": 0.5
+ }
+```
+
+`type`: non-null String - represents the type of policy implemented (at the moment, only `simple` has been implemented)
+
+`flat_fee`: float number that represents the fixed amount to pay
+
+`per_hour_fare`: float number that represents the amount to pay for each hour in the parking (each started hour is due)
+
 
 **Data example** all fields must be sent