fix: add the project description to the README

Author: leodevian

changelog.d/+b4ac60d4.fixed.md

@@ -0,0 +1 @@
+Add the project description to `README.md`.

template/README.md.jinja

@@ -8,8 +8,8 @@
 [![black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
 [![Ruff](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/astral-sh/ruff/main/assets/badge/v2.json)](https://github.com/astral-sh/ruff)
 [![uv](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/astral-sh/uv/main/assets/badge/v0.json)](https://github.com/astral-sh/uv)
-{% if description %}
-{{ description }}.
+{% if project_description %}
+{{ project_description }}.
 {% endif %}
 ## Installation