Update Readme.md 

Add via attribute

    Error: Collection user has an association attribute that is missing a `via` property. Any associations with a `collection` attribute must specify a `via` option that points to another attribute. Update the attribute: passports and add a `via` property
        at JoinTables.buildJoins
Merge pull request #7 from HaNdTriX/patch-1

Merge #7: Add via attribute to User model