Add faq that insert function can only be connected to one destination

Added the following faq that insert function can only be connected to one destination only.

"Can I connect an insert function to multiple destinations?

No, a destination insert function currently can be connected to one destinations only."

Author: tanjinhong72

src/connections/functions/insert-functions.md

@@ -315,6 +315,10 @@ No, Segment can't guarantee the order in which the events are delivered to an en
 
 No, destination insert functions are currently available as cloud-mode destinations only. Segment is in the early phases of exploration and discovery for supporting customer "web plugins" for custom device-mode destinations and other use cases, but this is unsupported today.
 
+##### Can I connect an insert function to multiple destinations?
+
+No, a destination insert function currently can be connected to one destinations only.
+
 ##### How do I publish a destination to the public Segment catalog?
 
 If you are a partner, looking to publish your destination and distribute your app through Segment catalog, visit the [Developer Center](https://segment.com/partners/developer-center/){:target="_blank"} and check out the Segment [partner docs](/docs/partners/).