SDL: Added a note that SDL_RenderReadPixels() should be called before SDL_RenderPresent()

SDL Commits
1 
From 40b7326b384aef84d3a688babb304bc2f333b6f7 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Fri, 18 Mar 2022 10:28:38 -0700
Subject: [PATCH] Added a note that SDL_RenderReadPixels() should be called
 before SDL_RenderPresent()

---
 include/SDL_render.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/SDL_render.h b/include/SDL_render.h
index c33094dbf67..53d699548d1 100644
--- a/include/SDL_render.h
+++ b/include/SDL_render.h
@@ -1662,7 +1662,8 @@ extern DECLSPEC int SDLCALL SDL_RenderGeometryRaw(SDL_Renderer *renderer,
  * Read pixels from the current rendering target to an array of pixels.
  *
  * **WARNING**: This is a very slow operation, and should not be used
- * frequently.
+ * frequently. If you're using this on the main rendering target, it
+ * should be called after rendering and before SDL_RenderPresent().
  *
  * `pitch` specifies the number of bytes between rows in the destination
  * `pixels` data. This allows you to write to a subrectangle or have padded