Content Security Policy Cheat Sheet with more info

[shaialon]

Thank you for submitting a Pull Request (PR) to the Cheat Sheet Series.

🚩 If your PR is related to grammar/typo mistakes, please double-check the file for other mistakes in order to fix all the issues in the current cheat sheet.

Please make sure that for your contribution:

• 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
• 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.

If your PR is related to an issue, please finish your PR text with the following line:

This PR covers issue #.

Thank you again for your contribution 😃

[jmanico]

Can you just link up caniuse for navigate-to and clarify the use of the term unsigned?

[jmanico]

Looks good

[jmanico]

great

[mackowski]

Looks good! Thank you!

[shaialon]

@jmanico , are we good to merge?
(it seems to be stuck pending your approval...)
Thanks.

[jmanico]

Great work!