Cookie Theft Mitigation Cheat Sheet

[Jxck]

Early draft of Cookie Theft Mitigation Cheat Sheet.

This PR fixes issue #1547

Guideline

• In case of a new Cheat Sheet, you have used the Cheat Sheet template.
• All the markdown files do not raise any validation policy violation, see the policy.
• All the markdown files follow these format rules.
• All your assets are stored in the assets folder.
• All the images used are in the PNG format.
• Any references to websites have been formatted as [TEXT](URL)
• You verified/tested the effectiveness of your contribution (e.g., the defensive code proposed is really an effective remediation? Please verify it works!).
• The CI build of your PR pass, see the build status here.

[szh]

I really like this document. I've left some proofreading suggestions but am quite excited about this.

[Jxck]

@szh Thanks for Review ! I fixed them up.

[szh]

LGTM, thank you!