patch 9.0.1146: MS-Windows: various special keys/modifiers are not mappable

Problem:    MS-Windows: various special keys and modifiers are not mappable.
Solution:   Adjust the handling of keys with modifiers. (Christian Plewright,
            closes #11768)
diff --git a/nsis/README.txt b/nsis/README.txt
index 31fa787..e1abc4a 100644
--- a/nsis/README.txt
+++ b/nsis/README.txt
@@ -29,12 +29,12 @@
 
 4.  Get a "diff.exe" program.  If you skip this the built-in diff will always
     be used (which is fine for most users).  If you do have your own
-    "diff.exe" put it in the "../.." directory (above the "vim82" directory,
+    "diff.exe" put it in the "../.." directory (above the "vim90" directory,
     it's the same for all Vim versions).
     You can find one in previous Vim versions or in this archive:
 		http://www.mossbayeng.com/~ron/vim/diffutils.tar.gz
 
-5   Also put winpty32.dll and winpty-agent.exe in "../.." (above the "vim82"
+5   Also put winpty32.dll and winpty-agent.exe in "../.." (above the "vim90"
     directory).  This is required for the terminal window.
 
 6.  Do "make uganda.nsis.txt" in runtime/doc.  This requires sed, you may have