added concat function

Author: muhammadatifjav

src/connections/destinations/actions.md

@@ -207,6 +207,9 @@ The coalesce function takes a primary value and uses it if it is available. If t
 
 The replace function allows you to replace a string, integer, or boolean with a new value. You have the option to replace up to two values within a single field.
 
+### Concatenate function
+You can concatenate two properties by using a pipe '|' character, or add the string value (e.g. +1`phoneNumber`) in the event variable field itself to concatenate. 
+
 ### Conditions
 
 > info ""