Improve go documentation

[Jerome1337]

Fixes #35

[codecov]

Codecov Report

Merging #38 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #38   +/-   ##
=======================================
  Coverage   80.76%   80.76%           
=======================================
  Files           9        9           
  Lines         130      130           
=======================================
  Hits          105      105           
  Misses         21       21           
  Partials        4        4           

Impacted Files	Coverage Δ
router/router.go	0.00% <ø> (ø)
router/writer.go	100.00% <ø> (ø)
services/reader.go	82.60% <ø> (ø)
services/sheet.go	100.00% <ø> (ø)

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