Adds documentation for bulk operations

[bmario]

Fixes #33

[codecov]

Codecov Report

Merging #37 (52f40d1) into master (563c6f7) will increase coverage by 0.10%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #37      +/-   ##
==========================================
+ Coverage   96.70%   96.81%   +0.10%     
==========================================
  Files          11       11              
  Lines         851      847       -4     
==========================================
- Hits          823      820       -3     
+ Misses         28       27       -1     

Impacted Files	Coverage Δ
aiocouch/document.py	90.69% <ø> (-1.84%)	⬇️
aiocouch/exception.py	98.50% <ø> (+5.17%)	⬆️
aiocouch/remote.py	96.38% <ø> (-0.02%)	⬇️
aiocouch/bulk.py	100.00% <100.00%> (ø)
aiocouch/database.py	100.00% <100.00%> (ø)
aiocouch/request.py	100.00% <0.00%> (ø)

---

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 563c6f7...52f40d1. Read the comment docs.