SDL: gendynapi.py: add comment for OS-specific API (Thanks @DanielGibson!)

From b116dd8eb84a2882275071e050df7ebaae99b0a9 Mon Sep 17 00:00:00 2001
From: Sylvain <[EMAIL REDACTED]>
Date: Fri, 9 Dec 2022 09:27:19 +0100
Subject: [PATCH] gendynapi.py: add comment for OS-specific API (Thanks
 @DanielGibson!)

---
 src/dynapi/gendynapi.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/dynapi/gendynapi.py b/src/dynapi/gendynapi.py
index db69f03ef55a..18c2e03b81a6 100755
--- a/src/dynapi/gendynapi.py
+++ b/src/dynapi/gendynapi.py
@@ -23,6 +23,11 @@
 #  When you add a public API to SDL, please run this script, make sure the
 #  output looks sane (git diff, it adds to existing files), and commit it.
 #  It keeps the dynamic API jump table operating correctly.
+#
+#  OS-specific API:
+#   After running the script, you have to manually add #ifdef __WIN32__
+#   or similar around the function in 'SDL_dynapi_procs.h'
+#
 
 import re
 import os