Footer changes

## Problem
There is a link in the bottom left of the footer called `Hydra` (https://www.joystream.org/hydra)

* I don't know if the page is relevant anymore? It contains some broken links (`Kusama Playground`)

Beyond this:
* The footer should really include the same links available as in the header, currently it is missing the following links: `Lightpaper`, `About`, `Community`, `Token`, `Governance`, `Manifesto`, `Handbook`

CC: @bedeho

Inspect the footer and header navigation entry points first, then compare their available links. Confirm whether the Hydra page and its Kusama Playground link are still relevant, and update the footer so the requested navigation links are present and outdated links are resolved. Done means the footer matches the intended header links and no longer exposes an inappropriate or broken Hydra destination.

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