fix sidebar ordering for highlights

[joshka]

Right now we have to manually order the highlight docs in the sidebar.

ratatui-website/astro.config.mjs

Lines 228 to 246 in 6561c34

	label: "Highlights",
	collapsed: true,
	items: [
	{
	label: "Highlights",
	link: "/highlights/",
	},
	{
	label: "v0.29",
	link: "/highlights/v029/",
	},
	{
	label: "v0.28",
	link: "/highlights/v028/",
	},
	{
	label: "v0.27",
	link: "/highlights/v027/",
	},

But it's possible to automatically order them apparently:

withastro/starlight#1872 (comment)