Add Source Function Alphabetization FAQ DOC-536

Author: pwseg

src/connections/functions/source-functions.md

@@ -394,3 +394,7 @@ The maximum payload size for an incoming webhook payload is 512 KiB.
 ##### What is the timeout for a function to execute?
 
 The execution time limit is five seconds, however Segment strongly recommends that you keep execution time as low as possible. If you are making multiple external requests you can use async / await to make them concurrently, which will help keep your execution time low.
+
+#### Does Segment alter incoming payloads?
+
+Segment alphabetizes payload fields that come in to **deployed** Source Functions. Segment doesn't alphabetize payloads in the Functions tester. If you need to verify the exact payload that hits a Source Function, alphabetize it first. You can then make sure it matches what the Source Function ingests.