There seems to be a duplicate `nftables-intro` tag in the documentation

[tristan957]

This error is reported by lazy.nvim when I update the plugin.

Vim:E154: Duplicate tag "nftables-intro" in file /.../.local/share/nvim/lazy/vim-syntax-nftables/doc/developer-notes/nftables.txt

It is used in both the Introduction and Usage sections of the documentation:

vim-syntax-nftables/doc/developer-notes/nftables.txt

Lines 27 to 43 in bfafd17

	1. Introduction *nftables-intro*
	You can do the following:
	* Highlight syntax used by nftables v1.2
	* Highlight files having `.nft` filetype.
	* unique color for each nested block denoted by a pair
	of brace/bracket/paranthesis.
	* tab ident by 4
	* highlight errors
	*E701*
	WARNING: Using nftables syntax is very powerful, and may lead to unexpected side
	effects.
	==============================================================================
	2. Usages *nftables-intro*

.