change Birmingham facts to bullet points

### Link to the curriculum page

https://curriculum.codeyourfuture.io/itp/onboarding/sprints/1/day-plan/

### Steps to reproduce

The 5 Birmingham facts on the Fun Facts website are numbered and should be shown as bullet points as per the requirements

从 Fun Facts 网站和链接的课程页面开始，找到 Birmingham facts 部分。定位五条编号事实，并将其呈现方式改为项目符号。完成标准是五条 Birmingham facts 全部以项目符号显示，并符合课程要求。

由索引模型根据 Issue 内容生成。