Improve doc

Author: gcatanese

tools/hmac/README.md

@@ -3,6 +3,8 @@
 This folder contains PHP scripts to calculate the HMAC signature of the webhook payload.  
 They can be used to troubleshoot the HMAC signature calculation.
 
+Check tools/hmac/package.json to confirm the Adyen Node API library version
+
 Note: make sure you are using the HMAC key used to generate the signature associated with the payload in the JSON file
 
 ### Payments webhooks
@@ -11,6 +13,10 @@ Copy the content of the webhook in the payload.json (or provide a different file
 `node calculateHmacPayments.js {hmacKey} {path to JSON file}`
 ```
 cd tools/hmac
+npm install 
+
+npm list @adyen/api-library // check version of library and update if needed
+
 node calculateHmacPayments.js 11223344D785FBAE710E7F943F307971BB61B21281C98C9129B3D4018A57B2EB payload.json
 ```