Add CONTRIBUTING.md and development.md

[majakurcius]

Description

Changes proposed in this pull request:

• Add the CONTRIBUTING.md document
• Add the docs/development.md document
• Add Contributing section to the main README.md
• Update docs/README.md's table of contents
• Delete duplicate issue templates

Related issue(s)

Resolves #18

[codecov]

Codecov Report

Merging #56 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #56   +/-   ##
=======================================
  Coverage   50.13%   50.13%           
=======================================
  Files          12       12           
  Lines         375      375           
=======================================
  Hits          188      188           
  Misses        183      183           
  Partials        4        4           

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[mszostok]