Add package-level docs for new persistent collections
Add package-level docs for new persistent collections

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