DOC: Finish docs for 0.8pre

[bashtage]

Finish docs with changes

[codecov-io]

Codecov Report

Merging #696 into master will decrease coverage by 21.04%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master     #696       +/-   ##
===========================================
- Coverage   83.87%   62.83%   -21.05%     
===========================================
  Files          61       61               
  Lines        2704     2704               
  Branches      301      301               
===========================================
- Hits         2268     1699      -569     
- Misses        362      938      +576     
+ Partials       74       67        -7

Impacted Files	Coverage Δ
pandas_datareader/iex/ref.py	0% <0%> (-100%)	⬇️
pandas_datareader/iex/stats.py	0% <0%> (-86.57%)	⬇️
pandas_datareader/av/forex.py	22.72% <0%> (-72.73%)	⬇️
pandas_datareader/tests/av/test_av_time_series.py	28.4% <0%> (-71.6%)	⬇️
pandas_datareader/tiingo.py	28.72% <0%> (-67.03%)	⬇️
pandas_datareader/av/quotes.py	26.47% <0%> (-64.71%)	⬇️
pandas_datareader/tests/test_tiingo.py	36.17% <0%> (-63.83%)	⬇️
pandas_datareader/quandl.py	29.26% <0%> (-63.42%)	⬇️
pandas_datareader/av/time_series.py	31.25% <0%> (-62.5%)	⬇️
pandas_datareader/oecd.py	34.78% <0%> (-60.87%)	⬇️
... and 18 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update f78ea2e...b2dde57. Read the comment docs.