feat: Implement hextra hero-section

[fmunteanu]

New Feature Proposal: Hero Section

On Hextra front-page, I need the ability to insert a h2 heading, defining additional section titles. For example, adding a subtitle above hextra/feature-grid.

Proposed Solution

I created the following layouts/shortcodes/hextra/hero-section.html shortcode, implementing a section.

Live Example

Visit https://axivo.com/k3s-cluster/.

Shortcode Usage

Example of hextra/hero-section shortcode usage, default header size is h2:

{{< hextra/hero-section >}}
  Used Technologies
{{< /hextra/hero-section >}}

Example of hextra/hero-section shortcode usage, with h3 header size:

{{< hextra/hero-section header="h3" >}}
  Used Technologies
{{< /hextra/hero-section >}}

Example of hextra/hero-section shortcode usage, with h4 or greater header size:

{{< hextra/hero-section header="h4" >}}
  Used Technologies
{{< /hextra/hero-section >}}

Frontage View

The Used Technologies section title, using default h2 header:

[netlify]

✅ Deploy Preview for hugo-hextra ready!

Name	Link
🔨 Latest commit	368c20e
🔍 Latest deploy log	https://app.netlify.com/sites/hugo-hextra/deploys/6647b02a66c07b0008c0065d
😎 Deploy Preview	https://deploy-preview-390--hugo-hextra.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[fmunteanu]

Related to #388 and #389.