update enum refs

Author: Francisco Liberal

pages/toolkits/productivity/jira/reference.mdx

@@ -4,6 +4,8 @@ Below is a reference of enumerations used by some tools in the Jira toolkit:
 
 ## SprintState
 
+Sprint states are used in the `Jira.ListSprints` tool to filter sprints. The following enumeration values represent the possible states supported by the Jira API, either individually or in combination:
+
 - **FUTURE**: `future`
 - **ACTIVE**: `active`
 - **CLOSED**: `closed`