Remove reference to old and new IP lists on REST API IP lPs page (#107)

A few months ago, the REST API IPs page was updated to remove 2 lists of old IP addresses (one for each of the service regions). The page text still had a reference to the old and new lists, so I have removed that in this PR as it is no longer the case.

docs/REST-API/19-REST-API-IPs.md

@@ -7,7 +7,7 @@ tags: [rest-api]
 
 This page lists the IP addresses that your system must be able to make outbound connections to on TCP port 443 to access our REST API in each of our service regions.
 
-The full list of IP addresses that our REST API may use is (separated between the old IP addresses and the new IP addresses):
+The full list of IP addresses that our REST API may use is:
 
 ## US Service Region