docs: privileges now on another page and not linked

[ghost]

Description

On this page, require_privilege and require__bot_privilege mention needing an int for permissions, but those are no longer on that page (they were in stable); they are now on this page.

It would be nice if there was a link to the relevant docs or something.

Reproduction steps

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Expected behavior

It would be nice if there was a link to the relevant docs or something.

Relevant logs

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Notes

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Sopel version

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Installation method

pip install

Python version

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Operating system

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IRCd

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Relevant plugins

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[ghost]

I can open a separate issue for "this should be an ENUM or otherwise handled better anyway", too, if you want, @dgw. :P