update typos in video descriptions and timecodes

[shiffman]

See: #1618

At the moment this can only be done by me manually, but I am open to giving edit access to video descriptions to someone and/or investigating doing these updates via the YouTube API.

[kfahn22]

I can handle this.

[kfahn22]

The typos in the challenges have been fixed.

[shiffman]

Wow!! So this can be closed?

[kfahn22]

updated matter.js and toxiclibs video descriptions

[kfahn22]

updated more-p5/pixel array

[kfahn22]

updated web sockets

[dipamsen]

@shiffman I am working on a script to automate updating the description via the YouTube API... (SEE #1621)

[kfahn22]

Love the idea of the automatic update -- in the meantime, ml5 and sound have been updated.

[kfahn22]

Updated the neural network videos. I believe I have updated everything.