Update documentation for Content Security Policy (CSP)

[Erasure5959]

Update relevant documentation to reflect new defaults for the Content Security Policy (CSP) after hardening.

Thank you for your contribution to the Pi-hole Community!

Please read the comments below to help us consider your Pull Request.

We are all volunteers and completing the process outlined will help us review your commits quicker.

Please make sure you

1. Base your code and PRs against the repositories developmental branch.
2. Sign Off all commits as we enforce the DCO for all contributions
3. Sign all your commits as they must have verified signatures
4. File a pull request for any change that requires changes to our documentation at our documentation repo

---

What does this PR aim to accomplish?:

This change aims to update the documentation for the default Content Security Policy as proposed in the FTL repository.

How does this PR accomplish the above?:

Update relevant documentation to reflect new defaults for the Content Security Policy (CSP) after hardening.

---

By submitting this pull request, I confirm the following:

1. I have read and understood the contributors guide, as well as this entire template. I understand which branch to base my commits and Pull Requests against.
2. I have commented my proposed changes within the code and I have tested my changes.
3. I am willing to help maintain this change if there are issues with it later.
4. It is compatible with the EUPL 1.2 license
5. I have squashed any insignificant commits. (git rebase)
6. I have checked that another pull request for this purpose does not exist.
7. I have considered, and confirmed that this submission will be valuable to others.
8. I accept that this submission may not be used, and the pull request closed at the will of the maintainer.
9. I give this submission freely, and claim no ownership to its content.

---

• I have read the above and my PR is ready for review. Check this box to confirm

[netlify]

✅ Deploy Preview for pihole-docs ready!

Name	Link
🔨 Latest commit	57fd4b7
🔍 Latest deploy log	https://app.netlify.com/projects/pihole-docs/deploys/695107fafe3ec10008d748ed
😎 Deploy Preview	https://deploy-preview-1332--pihole-docs.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[DL6ER]

@PromoFaux is this supposed to automagically update or is this PR needed?

[PromoFaux]

There will be an automagic PR once the FTL changes are merged to master.

[rdwebdesign]

The proposed FTL changes will only be effective after the next FTL release, which will automatically trigger the change here. So, this PR is not needed.

Also, [configfile.md] file contains a header explaining changes will be auto-generated:

docs/docs/ftldns/configfile.md

Lines 1 to 5 in 57fd4b7

	<!--!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	! DO NOT EDIT THIS FILE MANUALLY! !
	! THIS FILE IS AUTO-GENERATED FROM THE FTL REPO !
	!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
	-->

[github-actions]

This pull request has conflicts, please resolve those before we can evaluate the pull request.

[yubiuser]

This PR should be superseded by #1351

[github-actions]

Existing merge conflicts have not been addressed. This PR is considered abandoned.