Documentation improvements

[rofinn]

Closes #76

• Add an FAQ sections
• Document some design choices with references to other libraries, blog posts, issues and PRs
• Update usage guide to show off more common workflows

[codecov]

Codecov Report

Merging #83 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #83   +/-   ##
=======================================
  Coverage   87.40%   87.40%           
=======================================
  Files          12       12           
  Lines        1032     1032           
=======================================
  Hits          902      902           
  Misses        130      130           

Impacted Files	Coverage Δ
src/path.jl	84.12% <ø> (ø)

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