runtime(help): Update help syntax

This commit makaes the following changes to the vim help syntax:

- fix excessive URL detection in help, because `file:{filename}` in
  doc/options.txt is determined to be a URL.
- update highlighting N for :resize in help
- split Italian-specific syntax into separate help script
- highlight `Note` in parentheses in help
- update 'titlestring' behaviour in documentation for invalid '%' format

closes: #15883

Signed-off-by: Milly <milly.ca@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/syntax/help_it.vim b/runtime/syntax/help_it.vim
new file mode 100644
index 0000000..e76851d
--- /dev/null
+++ b/runtime/syntax/help_it.vim
@@ -0,0 +1,17 @@
+" Vim syntax file
+" Language:	Italian Vim program help files *.itx
+" Maintainer:	The Vim Project <https://github.com/vim/vim>
+" Last Change:	2024 Oct 16
+"
+" This script is sourced from syntax/help.vim.
+
+syn keyword helpNote		nota Nota NOTA nota: Nota: NOTA: notare Notare NOTARE notare: Notare: NOTARE:
+syn match helpNote		"\c(nota\(:\|\>\)"ms=s+1
+syn match helpSpecial		"Nma"me=e-2
+syn match helpSpecial		"Nme"me=e-2
+syn match helpSpecial		"Nmi"me=e-2
+syn match helpSpecial		"Nmo"me=e-2
+syn match helpSpecial		"\[interv.]"
+syn region helpNotVi		start="{non" start="{solo" start="{disponibile" end="}" contains=helpLeadBlank,helpHyperTextJump
+
+" vim: ts=8 sw=2