Update README.md

[Gonzalo-Mier]

Parent option is applied to the command "mkdir build" to prevent errors if the folder is already made. Other explanations are converted into "easier to execute" code.

I would like to participate in hacktoberfest with this pull request

[ZigRazor]

Good work!

[codecov-commenter]

Codecov Report

Merging #67 (4c893ae) into master (8b081e1) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #67   +/-   ##
=======================================
  Coverage   94.48%   94.48%           
=======================================
  Files          32       32           
  Lines        2937     2937           
=======================================
  Hits         2775     2775           
  Misses        162      162           

Flag	Coverage Δ
unittests	94.48% <ø> (ø)

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