SDL: docs: Add note about Wayland application icons

From 8321813452a2967449d31b6339dca8d0511c833d Mon Sep 17 00:00:00 2001
From: Frank Praznik <[EMAIL REDACTED]>
Date: Sun, 3 Sep 2023 10:33:01 -0400
Subject: [PATCH] docs: Add note about Wayland application icons

Wayland doesn't support programmatically setting the app icon, so note this restriction and specify that a desktop entry file that points to the desired icon image is required.
---
 docs/README-wayland.md | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/docs/README-wayland.md b/docs/README-wayland.md
index 7aefd192c9fb..5a0e44913215 100644
--- a/docs/README-wayland.md
+++ b/docs/README-wayland.md
@@ -34,3 +34,12 @@ encounter limitations or behavior that is different from other windowing systems
 ### Warping the global mouse cursor position via ```SDL_WarpMouseGlobal()``` doesn't work
 
 - For security reasons, Wayland does not allow warping the global mouse cursor position.
+
+### The application icon can't be set via ```SDL_SetWindowIcon()```
+
+- Wayland doesn't support programmatically setting the application icon. To provide a custom icon for your application,
+  you must create an associated desktop entry file, aka a `.desktop` file, that points to the icon image. Please see the
+  [Desktop Entry Specification](https://specifications.freedesktop.org/desktop-entry-spec/latest/) for more information
+  on the format of this file. Note that if your application manually sets the application ID via the `SDL_APP_ID` hint
+  string, the desktop entry file name should match the application ID. For example, if your application ID is set
+  to `org.my_org.sdl_app`, the desktop entry file should be named `org.my_org.sdl_app.desktop`.
\ No newline at end of file