Remove unimplemented modules; add inline documentation; update REAMD

[youming-lin]

Also, generated docs via jazzy. Alphabetized services and get functions.

@rfdickerson Can you review this?

[codecov-io]

Codecov Report

Merging #19 into master will not change coverage.
The diff coverage is 87.83%.

@@           Coverage Diff           @@
##           master      #19   +/-   ##
=======================================
  Coverage   74.52%   74.52%           
=======================================
  Files           2        2           
  Lines         318      318           
=======================================
  Hits          237      237           
  Misses         81       81

Flag	Coverage Δ
#CloudFoundryConfig	74.52% <87.83%> (ø)	⬆️
#HerokuConfig	?

Impacted Files	Coverage Δ
Sources/CloudFoundryConfig/Services.swift	77.41% <87.28%> (ø)	⬆️
Sources/CloudFoundryConfig/Extensions.swift	64.28% <90%> (ø)	⬆️

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