Update "About Pi-hole" link on "Website Blocked" page

[nfriend]

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• I have made only one major change in my proposed changes.
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What does this PR aim to accomplish?:

Updates the About Pi-hole link found on the Website Blocked page:

Currently, this link points to https://github.com/pi-hole/pi-hole/wiki/What-is-Pi-hole%3F-A-simple-explanation, which redirects to https://github.com/pi-hole/pi-hole/wiki, which instructs the user to instead visit https://docs.pi-hole.net/.

This PR updates the link to point directly to https://docs.pi-hole.net/.

How does this PR accomplish the above?:

Updates the hard-coded About Pi-hole link in advanced/index.php.

What documentation changes (if any) are needed to support this PR?:

None.

[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/pi-hole-core-web-v5-2-and-ftl-v5-3-released/40909/1