Added TWITTER_COOKIE example on quickstart.md

[haeunchin]

Background

What does this PR do?

For the Twitter-related .env file, TWITTER_COOKIES requires a specific JSON format with relevant information. Without an example, new developers may have difficulty configuring the Twitter environment.

What kind of change is this?

Added an example for TWITTER_COOKIES.

[ponderingdemocritus]

Twitter cookies should be optional, they are not actually needed unless you have cookies already

[monilpat]

LGTM! Feel free to to title it docs: title