Port @AntonioND 's Game Boy Camera documentation to Markdown

[avivace]

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Convert this https://github.com/AntonioND/gbcam-rev-engineer/blob/master/doc/gb_camera_doc.odt (by @AntonioND ) to markdown so we can include it in Pan Docs

[avivace]

On contributing to upstream / diverging: @AntonioND : yeah, but I think that anything I may own should only be used if you quote it as source of information, I would rather see you copy everything and ignore my repos. I can flag them as deprecated and link to the up-to-date doc

[AntonioND]

This issue can be closed, right? https://github.com/gbdev/pandocs/blob/5dbce5b026ab4bb373b1624ec70e72fe9001f02e/src/Gameboy_Camera.md