[CO-354] docs/how-to/launch-testnet.md: address discrimination
[CO-354] docs/how-to/launch-testnet.md: address discrimination

input-output-hk/cardano-sl,input-output-hk/pos-haskell-prototype,input-output-hk/pos-haskell-prototype,input-output-hk/cardano-sl,input-output-hk/cardano-sl,input-output-hk/cardano-sl,input-output-hk/pos-haskell-prototype