SDL: Added documentation for custom event cleanup in SDL_FlushEvent()

From 4fee6cb274f15a2f0fe20bdff50f85a34c2de5f2 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Thu, 18 Jan 2024 03:59:22 -0800
Subject: [PATCH] Added documentation for custom event cleanup in
 SDL_FlushEvent()

---
 include/SDL3/SDL_events.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/SDL3/SDL_events.h b/include/SDL3/SDL_events.h
index 32655f7c62c4..a6fb4ae0fc2d 100644
--- a/include/SDL3/SDL_events.h
+++ b/include/SDL3/SDL_events.h
@@ -823,6 +823,8 @@ extern DECLSPEC SDL_bool SDLCALL SDL_HasEvents(Uint32 minType, Uint32 maxType);
  * sure that all pending OS events are flushed, you can call SDL_PumpEvents()
  * on the main thread immediately before the flush call.
  *
+ * If you have user events with custom data that needs to be freed, you should use SDL_PeepEvents() to remove and clean up those events before calling this function.
+ *
  * \param type the type of event to be cleared; see SDL_EventType for details
  *
  * \since This function is available since SDL 3.0.0.