Add team_assignment_limit_change activity type to API version 2.14 (#326)

Adds OpenAPI documentation for team assignment limit changes in activity logs API for version 2.14 only.

Changes (version 2.14 only):
- Adds team_assignment_limit_change to activity_type enum (in alphabetical order)
- Adds team (object with id and name) metadata field
- Adds team_assignment_limit (nullable integer) metadata field

The metadata structure follows the pattern of conversation_assignment_limit and ticket_assignment_limit,
storing only the current value rather than both old and new values.

Note: This feature is available in version 2.14, not in the unreleased/unstable version.

Related PRs:
- intercom/intercom#446612 (Updated API presenter implementation)
- intercom/intercom#445742 (Initial API presenter implementation)
- intercom/intercom#445704 (Event infrastructure)

Related Issue: intercom/intercom#445916

Author: salmanbshah

descriptions/2.14/api.intercom.io.yaml

@@ -14119,6 +14119,7 @@ components:
           - seat_change
           - seat_revoke
           - security_settings_change
+          - team_assignment_limit_change
           - temporary_expectation_change
           - upfront_email_collection_change
           - welcome_message_change
@@ -14208,6 +14209,24 @@ components:
           nullable: true
           description: The ticket assignment limit value for an admin.
           example: 20
+        team:
+          type: object
+          nullable: true
+          description: Details about the team whose assignment limit was changed.
+          properties:
+            id:
+              type: integer
+              description: The ID of the team.
+              example: 123
+            name:
+              type: string
+              description: The name of the team.
+              example: Support Team
+        team_assignment_limit:
+          type: integer
+          nullable: true
+          description: The team assignment limit value (null if limit was removed).
+          example: 50
     addressable_list:
       title: Addressable List
       type: object