Add Debian Sid installation instructions (#2138)
Add Debian Sid installation instructions (#2138)

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cquinn/ponyc,Perelandric/ponyc,dipinhora/ponyc,boemmels/ponyc,Perelandric/ponyc,CausalityLtd/ponyc,dipinhora/ponyc,sgebbie/ponyc,Theodus/ponyc,cquinn/ponyc,ponylang/ponyc,boemmels/ponyc,cquinn/ponyc,kulibali/ponyc,cquinn/ponyc,CausalityLtd/ponyc,ponylang/ponyc,Theodus/ponyc,kulibali/ponyc,Perelandric/ponyc,boemmels/ponyc,sgebbie/ponyc,jemc/ponyc,kulibali/ponyc,sgebbie/ponyc,Theodus/ponyc,ponylang/ponyc,CausalityLtd/ponyc,Perelandric/ponyc,dipinhora/ponyc,Praetonus/ponyc,Theodus/ponyc,sgebbie/ponyc,kulibali/ponyc,Praetonus/ponyc,jemc/ponyc,sgebbie/ponyc,boemmels/ponyc,Praetonus/ponyc,Theodus/ponyc,Praetonus/ponyc,Perelandric/ponyc,jemc/ponyc,boemmels/ponyc