Add info section about client-side Klaviyo events (#4087)

* Add info section about client-side Klaviyo events

Let customers know that some Klaviyo events (such as Added to Cart) require that a user be identified first (i.e. cookied) in order to track a subsequent event.

* Update src/connections/destinations/catalog/klaviyo/index.md

Co-authored-by: markzegarelli <[email protected]>

Author: sarahrudy

src/connections/destinations/catalog/klaviyo/index.md

@@ -142,6 +142,9 @@ analytics.track({
 
 When you call `track` on `analytics.js`, Segment calls Klaviyo's `track` with the same parameters.
 
+> info ""
+> When you're tracking client-side, some Klaviyo events require you send an Identify call  before a Track call. 
+
 ### Server-side Track
 
 When you call make a Track call from one of Segment's mobile or server-side libraries, Segment keys the user with the `userId` and also provides the Klaviyo `$email` `customer_property` if your `userId` is an email, or you provide `email` as one of your event `properties`.