Add issue template

[Leko]

Fixed #89

[codecov-io]

Codecov Report

Merging #90 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #90   +/-   ##
=======================================
  Coverage   33.33%   33.33%           
=======================================
  Files          21       21           
  Lines         417      417           
  Branches       44       44           
=======================================
  Hits          139      139           
  Misses        252      252           
  Partials       26       26

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