patch 9.1.1058: translation(sr): Missing Serbian translation for the tutor

Problem:  translation(sr): Missing Serbian translation for the tutor
Solution: include new Serbian translation for the new tutor,
          include translation for chapter 2 of the traditional tutor,
          update the Makefiles for installing the runtime files
          (Ivan Pešić)

closes: #16550

Signed-off-by: Ivan Pešić <27575106+eevan78@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/tutor/tutor.vim b/runtime/tutor/tutor.vim
index 1ca4b2d..6e63937 100644
--- a/runtime/tutor/tutor.vim
+++ b/runtime/tutor/tutor.vim
@@ -132,7 +132,7 @@
   endif
 endif
 
-" The Slovak tutor is available in two encodings, guess which one to use
+" The Serbian tutor is available in two encodings, guess which one to use
 " Note that the utf-8 version is the original, the cp1250 version is created
 " from it.
 if s:ext =~? '\.sr'