Add notes regarding parameters format to trade and order endpoints

README.md

@@ -369,7 +369,7 @@ Places a limit order on IDEX. The JSON object passed as input to this API call m
 * r - ... 
 * s - (v r and s are the values produced by your private key signature, see above for details)
 
-Example request body:
+Example request body (Note that both `amountBuy` and `amountSell` fields should be converted to string):
 
 ```js
 {
@@ -489,6 +489,8 @@ Apply the salt and hash the result as usual, then sign your salted hash.
 
 NOTE: Currently, all orders being filled in a trade must be for the same tokenBuy/tokenSell pair, and must all be signed from the same address
 
+Make sure to convert `amount` field to string when sending it with JSON payload.
+
 Sample output:
 
 ```js