Feature Request: Preload `System.Memory` NuGet package

[BillWagner]

This package is required for any samples that use Span<T> and friends. See dotnet/docs#6225 (comment) for details.

/cc @pkulikov

[pkulikov]

Related (or duplicate) of #85

[LadyNaggaga]

@TheRealPiotrP @colombod @jonsequitur could we please get the above NuGet package added.

[pkulikov]

As for now, try.dot.net accepts Span<T>. @LadyNaggaga thanks a lot!