Docs: list of resellers that deliver hardware with Heads firmware

[wessel-novacustom]

Is your feature request related to a problem? Please describe.
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Currently, there is no list of known resellers that deliver hardware with Heads firmware.

Describe the solution you'd like
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A list with known resellers that deliver hardware with Heads firmware.

What's the additional value?

• People who don't want to open their devices and flash manually can choose a reseller easily, without having to search online for options. There are a lot of potential users for whom Heads' concept would be perfect, but need a straight-forward solution with Heads preinstalled.