Update searchable-snapshots.md (elastic#3313)

Added a note that searchable snapshots are an enterprise license feature

Author: perrinal

deploy-manage/tools/snapshot-and-restore/searchable-snapshots.md

@@ -12,6 +12,9 @@ products:
 ---
 
 # Searchable snapshots [searchable-snapshots]
+::::{important}
+Searchable snapshots is a feature that requires an Enteprise license. 
+::::
 
 {{search-snaps-cap}} let you use [snapshots](../snapshot-and-restore.md) to search infrequently accessed and read-only data in a very cost-effective fashion. The [cold](../../../manage-data/lifecycle/data-tiers.md#cold-tier) and [frozen](../../../manage-data/lifecycle/data-tiers.md#frozen-tier) data tiers use {{search-snaps}} to reduce your storage and operating costs.