[ADAM-890] Adding examples of how to use joins in the real world
[ADAM-890] Adding examples of how to use joins in the real world

Resolves #890.
bigdatagenomics/adam,laserson/adam,bigdatagenomics/adam,laserson/adam,laserson/adam,heuermh/adam,laserson/adam,heuermh/adam,bigdatagenomics/adam,heuermh/adam,heuermh/adam,bigdatagenomics/adam