sdl12-compat: README: change to Markdown format.

From 8f7067c9958b5595197a632e6e63fa73c23a96d2 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Sun, 4 Apr 2021 12:33:09 -0400
Subject: [PATCH] README: change to Markdown format.

---
 README.txt => README.md | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)
 rename README.txt => README.md (83%)

diff --git a/README.txt b/README.md
similarity index 83%
rename from README.txt
rename to README.md
index 910ef9c..9bb9fed 100644
--- a/README.txt
+++ b/README.md
@@ -1,11 +1,5 @@
+# Simple DirectMedia Layer (SDL) sdl12-compat
 
-                         Simple DirectMedia Layer
-
-                                  (SDL)
-
-                               sdl12-compat
-
----
 https://www.libsdl.org/
 
 This is the Simple DirectMedia Layer, a general API that provides low