Merge pull request #2222 from sanscontext/patch-2

Clarify wording on timestamps + Personas note

Author: stayseesong

src/connections/spec/common.md

@@ -302,10 +302,10 @@ Sending data to the rest of our destinations is opt-out so if you don't specify
 
 Every API call has four timestamps, `originalTimestamp`, `timestamp`, `sentAt` and `receivedAt.`  They're used for very different purposes.
 
-**All timestamps are [ISO-8601](http://en.wikipedia.org/wiki/ISO_8601) date strings.**
+**All timestamps are [ISO-8601](http://en.wikipedia.org/wiki/ISO_8601){:target="_blank"} date strings.**
 
 > note ""
-> **NOTE:** ISO-8601 date strings with timezones included are required when using timestamps with [Personas](/docs/personas/). Sending custom traits without a timezone included in the timestamp will result in the value not being saved.
+> **NOTE:** You must use ISO-8601 date strings that include timezones when you use timestamps with [Personas](/docs/personas/). If you send custom traits without a timezone, Segment doesn't save the timestamp value.
 
 ### Timestamp Overview