patch 8.1.1069: source README file doesn't look nice on github

Problem:    Source README file doesn't look nice on github.
Solution:   Turn it into markdown, still readable as plain text.
            (WenxuanHuang, closes #4141)

src/version.c

@@ -775,6 +775,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1069,
 /**/
     1068,
 /**/