[BD-3303] Clarify CDN directives for Web SDK

[internetisaiah]

Why are you making this change? (required)

From ticket:

We list the braze CDN url as required for img-src but if a user is using custom fonts, for example, in In-App Messages, they'll need font-src to include the braze CDN url as well.

Note: I converted the sections to use tables instead as it makes copying and pasting much easier for readers (now you just need to triple-click in the cell instead of manually highlighting with mouse).

Related PRs, issues, or features (optional)

• BD-3303

Feature release date (optional)

• N/A

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