patch 9.1.0901: MS-Windows: vimtutor batch script can be improved

Problem:  MS-Windows: vimtutor batch script can be improved
Solution: Update vimtutor.bat, validate languages using Powershell
          cultureinfo (RestorerZ)

closes: #16112

Signed-off-by: RestorerZ <restorer@mail2k.ru>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/vimtutor b/src/vimtutor
index 409c10c..1d530d4 100755
--- a/src/vimtutor
+++ b/src/vimtutor
@@ -50,6 +50,7 @@
 it Italian \
 ja Japanese \
 ko Korean \
+lt Lithuanian \
 lv Latvian \
 nb Bokmål \
 nl Dutch \
@@ -61,7 +62,7 @@
 sr Serbian \
 sv Swedish \
 tr Turkish \
-uk English \
+uk Ukrainian \
 vi Vietnamese \
 zh Chinese