runtime(vim): update Vim Syntax generator

- Add missing "Last Change:" line.
- The date on this line in vim.vim is updated by update_date.vim at
  Make time. (I made a mistake in the file path)
- Remove unnecessary "b:loaded_syntax_vim_ex".
- Remove "Base File Date:" line in vim.vim.base
- Add Doug Kearns as Maintainer

closes: #14031

Signed-off-by: h-east <h.east.727@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/syntax/generator/gen_syntax_vim.vim

@@ -248,6 +248,7 @@ function! s:parse_vim_command(cmd)
 		let item.syn_str = item.name
 		call add(a:cmd, copy(item))
 		let item.name = 'i'		" insert
+		let item.syn_str = item.name
 		call add(a:cmd, copy(item))
 
 		if empty(a:cmd)
@@ -445,6 +446,16 @@ function! s:parse_vim_hlgroup(li)
 		let item.type = 'gui'
 		call add(a:li, copy(item))
 
+		" The following highlight groups cannot be extracted from highlight.c
+		" (TODO: extract from HIGHLIGHT_INIT ?)
+		let item.name = 'LineNrAbove'
+		let item.type = 'both'
+		call add(a:li, copy(item))
+
+		let item.name = 'LineNrBelow'
+		let item.type = 'both'
+		call add(a:li, copy(item))
+
 		quit!
 
 		if empty(a:li)