Improve i18n, 404, contact page, OG metadata and more

[salim-b]

• improve i18n:

  • add German translation, improve French translation, tweak English translation
  • move translation (i18n folder) from /exampleSite to theme root; this is cleaner; theme users can still override translation keys individually of course
  • order i18n keys alphabetically

• improve contact page:

  • translate placeholders
  • reorganize contact-page-related keys in config.toml more logically
  • allow to disable contact form via config.toml
  • allow to remove address compontents (e-mail, phone nr, location) individually
  • add support for Netlify Forms as contact form provider (incl. a honey pot field)
  • make all contact form fields mandatory by adding the required attribute
  • opt-in support for omission of address descriptors (icons should already be self-explanatory) via config.toml

• improve 404 page:

  • translate 404 page; note that you have to instruct your HTTP server to serve the language-specific 404 pages, for Netlify add redirect rules à la:

    # French subpages 404
    [[redirects]]
    from = "/fr/*"
    to = "/fr/404.html"
    status = 404
    
    # all other pages 404 (incl. those in `defaultContentLanguage`)
    # NOTE that in case you've set `defaultContentLanguageInSubdir = true` in `config.toml`, you need to change the destination below to point to the `defaultContentLanguage` subdir, e.g. `to = "/en/404.html"`
    [[redirects]]
    from = "/*"
    to = "/404.html"
    status = 404

  • fix copyright info in 404 page footer
  • remove duplicate site logo from 404 page (is already in page header which is included in the 404 page)

• improve OpenGraph / Twitter Card metadata

  • add Hugo's internal Twitter Card template
  • add params.title to config.toml in order to enable og:site_name tags
  • add params.images to config.toml in order to enable fallback for og:image tags

• improve FAQ page

  • fix last modification date: .Lastmod is automatically complemented by date and publishDate, so no need for custom logic
  • replace address info with autogenerated table of contents -> makes much more sense for an FAQ page :)

• clean/tidy config.toml:

  • remove orphaned [params.nav_button] (isn't used anywhere in the theme)
  • fix Google Analytics ID key name (correct is googleAnalytics)
  • harmonize capitalization of keys, cf. https://github.com/themefisher/airspace-hugo/pull/116
  • reorganize keys
  • improve comments

[somratpro]

@salim-b

Please resolve conflicts

[salim-b]

Merge conflicts resolved ✅