SDL: docs(gpu): document depth texture limitation in SDL_CopyGPUTextureToTexture (#14693)

From 00fe482efb56bf239f1b09d8b2357fc503c7cce0 Mon Sep 17 00:00:00 2001
From: "Edgar San Martin, Jr." <[EMAIL REDACTED]>
Date: Mon, 22 Dec 2025 11:25:32 -0500
Subject: [PATCH] docs(gpu): document depth texture limitation in
 SDL_CopyGPUTextureToTexture (#14693)

---
 include/SDL3/SDL_gpu.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/SDL3/SDL_gpu.h b/include/SDL3/SDL_gpu.h
index 1de5c704741e9..459551ef6e5dd 100644
--- a/include/SDL3/SDL_gpu.h
+++ b/include/SDL3/SDL_gpu.h
@@ -3903,6 +3903,9 @@ extern SDL_DECLSPEC void SDLCALL SDL_UploadToGPUBuffer(
  * This copy occurs on the GPU timeline. You may assume the copy has finished
  * in subsequent commands.
  *
+ * This function does not support copying between depth and color textures. For
+ * those, copy the texture to a buffer and then to the destination texture.
+ *
  * \param copy_pass a copy pass handle.
  * \param source a source texture region.
  * \param destination a destination texture region.