Smart List vs Static List clarity

[tmayse]

Issue in ./help/marketo/product-docs/core-marketo-concepts/smart-lists-and-static-lists/static-lists/send-a-list-to-adobe-experience-cloud.md

This doc implies that continuous sync applies exclusively to Static Lists, but it isn't very clear about the fact that Smart Lists don't offer the option to keep the list in sync. Clarifying that keeping the list in-sync is exclusive to static lists could help deflect some support cases.