appended newline to DataFrame.info() output
DOC: created advanced indexing section
DOC: add internals section (GH4082)
Merge pull request #8204 from jreback/doc

DOC: reorg indexing docs
Merge pull request #8114 from BorisVerk/master

BUG: fixed df.info() output missing new line
DOC: Correct and expand Series.nonzero docstring

- Mention that a tuple of indices is returned and explain why.
- Instead of numpy.ndarray.nonzero, point to numpy.nonzero, which has
  the full documentation.
- Add example.