fix(website): fix title tags

[yanthomasdev]

Summary

Starlight's title option was misconfigured by including an empty string (""). I believe this was done to use a logo-only title, but Starlight offers a proper option for this with logo.replacesTitle: true. In resume, this PR adds the correct configuration, fixing:

• Title tags being generated as, for example, Getting Started | rather than Getting Started | Biome.
• The home page link in the logo missing a sr-only text, meaning no a11y.

Note that now the home page biomejs.dev would have a title of Biome | Biome, but I've changed the head.title frontmatter property to only Biome. Feel free to use another name for the home page if you prefer.

Test Plan

By visually inspecting the website, you can see the browser's tab title following <page title> | Biome.

Also, by Inspecting the logo with Dev Tools you will now be able to see the following:

<span class="sr-only astro-onp6g3ne"> Biome </span>

rather than:

<span class="astro-hdkvlegf">  </span>

[ematipico]

Thank you Yan! Your expertise is very welcome 🙏