add documentation on how to write migration working with a custom user model
add documentation on how to write migration working with a custom user model

BryceLohr/authentic,pu239ppy/authentic2,adieu/authentic2,pu239ppy/authentic2,pu239ppy/authentic2,pu239ppy/authentic2,BryceLohr/authentic,adieu/authentic2,adieu/authentic2,BryceLohr/authentic,adieu/authentic2,BryceLohr/authentic