Deploy to GitHub Pages: Improve doc for generic base URL config and favicon working on <owner>.github.io/<repository>/

[mhoffrog]

Proposal for Improvement

Current doc of Deploy Nuxt to GitHub Pages / github-pages.md should be enhanced by the following helpful details:

1. Add a hint to generically set NUXT_APP_BASE_URL within a GitHub Action by:
   NUXT_APP_BASE_URL="/${GITHUB_REPOSITORY##*/}/" - so it works for any repo oob.

2. Give an example how to make favicon working in any case - for a custom domain as well as for hosting on <owner|organization>.github.io within nuxt.config.ts:

// https://nuxt.com/docs/api/configuration/nuxt-config
export default defineNuxtConfig({
  app: {
    head: {
      title: "My Page Title",
      link: [
        // https://nuxt.com/deploy/github-pages and https://vite.dev/guide/env-and-mode.html for details.
        // !!! Make use of compile time environment var NUXT_APP_BASE_URL to work for GitHub Pages deployments as well.
	// Assumption: favicon files in ~/public as ~/public/favicon.ico, ~/public/favicon-32x32.png etc.:
        {
          rel: "icon",
          type: "image/x-icon",
          href: (import.meta.env.NUXT_APP_BASE_URL ? import.meta.env.NUXT_APP_BASE_URL : "/") + "favicon.ico?x=2"
        },
        { 
          rel: "icon", type: "image/png", sizes: "32x32",
          href: (import.meta.env.NUXT_APP_BASE_URL ? import.meta.env.NUXT_APP_BASE_URL : "/") + "favicon-32x32.png"
        },
       // ... add probable other icon variants accordingly
      ],
    },
  },
  // ... continue with existing config
});