create material to explain neural networks

[stevehadd]

explain back propogration
highlight key hyperparameters from networtk architecture (feed forward) and back propogation training
show neural networks in tensorflow to dig down into structure a bit
show classification output vs regression output
show construction of different architectures

• feed forward
• convolutional
• LSTM (simple example? maybe using rotors as a time series?)
• Graph NN

[stevehadd]

this has mostly been done now. Just need to finish the recurrent nerual network example, which is covered by #11 .