Revised Centrifuge docs (#585)

* Fix mainnet (docker compose)

* Centrifuge docker compose revisedd

* Revise Testnet standalone setup

* chore: update demo spec

* Review after testing docker and binaries (tesnet)

* Add snapshots and new relaychain fast sync option

* quickly review the rest of the arguments

* Minor fixes after having validators try Centrifuge

* Added new bootnode for testnet

* PR comments

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Co-authored-by: William Freudenberger <w.freude@icloud.com>
Co-authored-by: Jeroen Offerijns <jeroen@offerijns.com>
Co-authored-by: Jeroen <1748621+hieronx@users.noreply.github.com>