Use GitHub Copilot instructions to generate Astro blog post frontmatter

Edit .github/copilot-instructions.md

Customize the instructions to reflect your frontmatter definition.

// .github/copilot-instructions.md

# Copilot Instructions

## Blog Posts

We store all blog posts inside the `src/content/blog` directory. All blog posts needs to have a front matter in YAML format. The description field should be a SEO friendly summary that can be generated from the content of the blog post and should not be longer than 150 words.

```yaml
---
author: Christoph Kieslich
date: "2024-03-22"
title: Getting started with a new Astro homepage
featured: true
draft: false
tags:
  - docs
description: Short description, maximum 150 wods
---
```