Minor improvements for Contributing page

[fremdev]

What: Add correct link and remove duplication in Contributing page

Why: To give some rest to Google :)

How: Edit contributing page

Checklist:

• [x ] Documentation
• [x ] Tests
• [x ] Ready to be merged
• [ ] Added myself to contributors table

[codecov[bot]]

Codecov Report

Merging #54 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #54   +/-   ##
=======================================
  Coverage   82.82%   82.82%           
=======================================
  Files           1        1           
  Lines         163      163           
  Branches       48       48           
=======================================
  Hits          135      135           
  Misses          9        9           
  Partials       19       19

---

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 6e24571...c140421. Read the comment docs.

[darrenjennings]

Thanks @fremdev!