runtime(doc): update vim90 to vim91 in docs

closes: #15747

Signed-off-by: mikoto2000 <mikoto2000@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/READMEdir/README_bindos.txt b/READMEdir/README_bindos.txt
index fd9b769..b1907dd 100644
--- a/READMEdir/README_bindos.txt
+++ b/READMEdir/README_bindos.txt
@@ -2,7 +2,7 @@
 
 See "README.txt" for general information about Vim.
 See "README_dos.txt" for installation instructions for MS-DOS and MS-Windows.
-These files are in the runtime archive (vim90rt.zip).
+These files are in the runtime archive (vim91rt.zip).
 
 
 There are several binary distributions of Vim for the PC.  You would normally