added content title to table for js-core-3 week 4.

[codedevbrad]

What does this change?

Module: Week(s):

Checklist

• [x] I have read the contributing guidelines
• [x] I have checked my spelling and grammar with an automated tool
• [x] I have previewed my changes to check the markdown renders as I intend
• [x] I have run my code to check it works
• [x] My changes follow our Style Guide

Description

Resolved an issue where the content table in the JavaScript Core 3 overview page was missing the title for Week 4, causing a discrepancy in the table structure.