Rename/document hrpc.Families to indicate that you can specify column qualifiers

[tomasbanet]

It is not immediately clear when creating a Scan request how one should specify the columns in a row that they are interested in retrieving.

After seeing some existing code written by others I saw that you can use the tsuna/gohbase/hrpc/query.go:Families option to specify the family as a key and the list of columns (qualifiers) in the family as a string slice in a map to get those families/columns in the result.

We should add some comments documenting what the Families map keys and values are supposed to represent. Alternatively rename the option to something like FamiliesWithColumns or FamiliesWithQualifiers to indicate that column selection is supported.

[dethi]

Right, I think the best would be to add documentation. Don't really think the other two functions would make sense. Wanna contribute and make the change? :)

[tomasbanet]

Sure. I'll add it to the godoc