nested_fields, data_exploration, importing_data

https://192.168.0.167:8888/docs/data-exploration/
https://192.168.0.167:8888/docs/importing/
https://192.168.0.167:8888/docs/nested-fields/javascript/
https://192.168.0.167:8888/docs/nested-fields/python/
https://192.168.0.167:8888/docs/nested-fields/ruby/

CC @ahruygt @mglukhovsky