Webpack: Fix HtmlWebpackPlugin script tag reference

[Maddily]

Because

This PR corrects the explanation of HtmlWebpackPlugin’s behavior in the Webpack lesson. The previous text inaccurately stated that HtmlWebpackPlugin adds a script tag to the main.js file. The update clarifies that HtmlWebpackPlugin actually adds the script tag to the index.html file.

This PR

• Updated the lesson text to specify that the script tag is added to index.html rather than main.js.

Issue

Closes #XXXXX

Additional Information

N/A

Pull Request Requirements

• I have thoroughly read and understand The Odin Project curriculum contributing guide
• The title of this PR follows the location of change: brief description of change format, e.g. Intro to HTML and CSS lesson: Fix link text
• The Because section summarizes the reason for this PR
• The This PR section has a bullet point list describing the changes in this PR
• If this PR addresses an open issue, it is linked in the Issue section
• If any lesson files are included in this PR, they have been previewed with the Markdown preview tool to ensure it is formatted correctly
• If any lesson files are included in this PR, they follow the Layout Style Guide

[MaoShizhong]

Good catch, silly error!