updated charge api

docs/api.md

@@ -59,13 +59,15 @@ Successfull discharge will have a response code of `201`
 ## `POST /api/json/key/:key/charge`
 
 Charges a key by specified amount. Creates a Order to do so. A note can be attached to the Order.  
-`manual` is currently the only valid payment processor for API.
+`manual` is currently the only valid payment processor for API.  
+Can take either amount or price. If both supplied only amount is taken into account.
 
 ### Parameters
 
 ```json
 {
-    "amount": <AMOUNT_TO_CHARGE>
+    "amount": <AMOUNT_TO_CHARGE>,
+    "price": <PRICE_TO_CHARGE>,
     "payment_processor": "manual",
     "note": <NOTE_FOR_ORDER>
 }