Remove or fix info that's wrong or not-yet right

[SidHarder]

Outdated things like multidaddrs that are not valid anymore, in presentations and other material

[ghost]

Updated title to: Remove or fix info that's wrong or not-yet right

In documentation cases, we want to strike out the wrong information, and I think we should add a "helpi fixing it" link.

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This will sometimes be info that's not neccessarily wrong, but was just simplified in order to bring a point accross. In these cases, we should note it's simplified and optionally mention the correct form.

[Mr0grog]

Since we rebooted this repo, the site is live, and we have at least a little ongoing contribution, I’m marking this as fixed. Please comment if it should be re-opened.