Further readme updates

Author: richardewell1862

README.md

@@ -16,15 +16,18 @@ The API provides two core capabilities:
 2. Search SIC Codes by Description
    Retrieve SIC Codes whose Descriptions contain a given keyword.
 
+Interactive API documentation (Postman): https://documenter.getpostman.com/view/6869909/2sBXc8oPEn
+
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 ## AUTHENTICATION
 
-- To access this API you need a RapidAPI API key
-- Create a free RapidAPI.com account
-- Search for the SICCodeAPI service in API Hub and subscribe to the free plan
-- RapidAPI will provide an API key that can be used immediately
-- No additional authentication setup is required
+- This API is distributed via RapidAPI
+- To execute requests, you’ll need a free RapidAPI account and API key
+- Create a free account at rapidapi.com.
+- Subscribe to the SICCodeAPI free plan in the RapidAPI API Hub.
+- RapidAPI issues an API key immediately upon subscription.
+- No additional authentication or setup is required.
 
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