[ADD] documentation for pipelines and steps

[ravinkohli]

Addresses #327

[codecov]

Codecov Report

Merging #329 (88f0f25) into development (f6af46f) will decrease coverage by 0.22%.
The diff coverage is 100.00%.

@@               Coverage Diff               @@
##           development     #329      +/-   ##
===============================================
- Coverage        82.01%   81.79%   -0.23%     
===============================================
  Files              152      152              
  Lines             8674     8677       +3     
  Branches          1325     1325              
===============================================
- Hits              7114     7097      -17     
- Misses            1093     1113      +20     
  Partials           467      467              

Impacted Files	Coverage Δ
autoPyTorch/api/tabular_classification.py	87.50% <ø> (ø)
autoPyTorch/api/tabular_regression.py	96.87% <ø> (ø)
autoPyTorch/pipeline/base_pipeline.py	71.57% <ø> (ø)
autoPyTorch/pipeline/components/base_choice.py	83.33% <ø> (ø)
autoPyTorch/pipeline/components/base_component.py	80.95% <ø> (-1.91%)	⬇️
autoPyTorch/pipeline/tabular_classification.py	74.57% <ø> (ø)
autoPyTorch/pipeline/tabular_regression.py	82.65% <ø> (ø)
...rch/pipeline/traditional_tabular_classification.py	73.68% <100.00%> (+0.35%)	⬆️
...PyTorch/pipeline/traditional_tabular_regression.py	28.33% <100.00%> (+2.47%)	⬆️
...eline/components/setup/optimizer/base_optimizer.py	71.42% <0.00%> (-19.05%)	⬇️
... and 13 more

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[nabenabe0928]

Thanks for the PR.
Your changes look mostly good to me.

[nabenabe0928]

What is this file for? I mean how I should read this doc?

[ravinkohli]

So this file basically contains the API documentation for AutoPyTorch. If you would like to take a look, you can make the docs locally on your laptop and then browse the HTML.

You need to do

pip install -e .[doc,examples]
cd docs
make html