runtime(vimtutor): Add a second chapter

fixes: #5719
closes: #5729

Signed-off-by: Paul Desmond Parker <pauldesmondparker@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/tutor/tutor.vim b/runtime/tutor/tutor.vim
index 809fd1d..551231a 100644
--- a/runtime/tutor/tutor.vim
+++ b/runtime/tutor/tutor.vim
@@ -180,8 +180,13 @@
   let s:ext .= '.utf-8'
 endif
 
-" 2. Build the name of the file:
-let s:tutorfile = "/tutor/tutor"
+" 2. Build the name of the file and chapter
+let s:chapter = exists("$CHAPTER") ? $CHAPTER : ''
+if s:chapter == "1"
+  let s:chapter = ''
+endif
+
+let s:tutorfile = "/tutor/tutor" . s:chapter
 let s:tutorxx = $VIMRUNTIME . s:tutorfile . s:ext
 
 " 3. Finding the file: