Update proposals/4354-sticky-events.md

Co-authored-by: Johannes Marbach <n0-0ne+github@mailbox.org>

proposals/4354-sticky-events.md

@@ -37,6 +37,8 @@ This new primitive can be used to implement MatrixRTC participation, live locati
 Message events can be annotated with a new top-level `sticky` key, which MUST have a `duration_ms`,
 which is the number of milliseconds for the event to be sticky. The presence of `sticky.duration_ms`
 with a valid value makes the event “sticky”[^stickyobj]. Valid values are the integer range 0-3600000 (1 hour).
+For use cases that require stickiness beyond this limit, the application is responsible for sending another
+event to make it happen.
 
 ```json
 {