[issue-1230] fix: fix docs to correctly reflect working example

[joeyklee]

Dear ml5 community,

I'm making a Pull Request(PR). Please see the details below.

A good PR 🌟

→ Step 1: Describe your Pull Request 📝

Fixing a Bug? Adding an Update? Submitting a New Feature? Does it introduce a breaking change?

Fixes #1230

A great PR 🌟🌟

→ Step 2: Share a Relevant Example 🦄

Here's some example code or a demonstration of my feature as a part of this pull request, a separate pull request, in the https://editor.p5js.org, or codepen/jsfiddle/etc...

Updates the docs to correctly demo the example as shown in the neural net docs

The best PR 🌟🌟🌟

→ Step 3: Screenshots or Relevant Documentation 🖼

Here's some helpful screenshots and/or documentation of the new feature

[shiffman]

Thanks for reminding me about this @joeyklee looks great!!!