SDL: SDL_revision: Added documentation.

From a15a46340f191ef09402cc49f22892a094bb5b40 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Tue, 9 Apr 2024 18:02:30 -0400
Subject: [PATCH] SDL_revision: Added documentation.

---
 include/SDL3/SDL_revision.h | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/include/SDL3/SDL_revision.h b/include/SDL3/SDL_revision.h
index badf017d18ce6..7c41b3aa59463 100644
--- a/include/SDL3/SDL_revision.h
+++ b/include/SDL3/SDL_revision.h
@@ -28,7 +28,21 @@
 #ifndef SDL_revision_h_
 #define SDL_revision_h_
 
-#ifdef SDL_VENDOR_INFO
+#ifdef SDL_WIKI_DOCUMENTATION_SECTION
+/**
+ * This macro is a string describing the source at a particular point in development.
+ *
+ * This string is often generated from revision control's state at build time.
+ *
+ * This string can be quite complex and does not follow any standard.
+ * For example, it might be something like "SDL-prerelease-3.1.1-47-gf687e0732".
+ * It might also be user-defined at build time, so it's best to treat it as
+ * a clue in debugging forensics and not something the app will parse in any way.
+ *
+ * \since This macro is available since SDL 3.0.0.
+ */
+#define SDL_REVISION "Some arbitrary string decided at SDL build time"
+#elif defined(SDL_VENDOR_INFO)
 #define SDL_REVISION SDL_VENDOR_INFO
 #else
 #define SDL_REVISION ""