Create a Child Theme for Astra

### Description

**Child themes** are extensions of a parent theme. They allow you to modify an existing theme without directly editing that theme’s code.

### Benefits of using child themes:

- Make your modifications portable and replicable.
- Keep customizations separate from the parent theme.
- Allow parent themes to be updated without losing your modifications.
- Save on development time since you’re only writing the code you need.

Reference: https://developer.wordpress.org/themes/advanced-topics/child-themes/

### Task:

- [x] Create a `style.css` with the required header.
- [x] Install and activate child theme