vim-patch:7.4.1425

Problem:    There are still references to MS-DOS support.
Solution:   Remove most of the help txt and install instructions. (Ken Takata)

6e722e2f94

src/nvim/version.c

@@ -76,6 +76,7 @@ static int included_patches[] = {
   1574,
   1570,
   1511,
+  1425,
   1366,
 
   // 1219 NA