feature: add stopEarly option

[jorgebucaran]

Add new stopEarly boolean property to the configuration options. If true, the operands array _ will be populated with all the arguments after the first non-option.

getopts(["-w9", "alpha", "--turbo", "beta"], {
  stopEarly: true
}) //=> { _:["alpha", "--turbo", "beta"], w:9 }

This property is useful when implementing sub-commands in a CLI as described by @julien-f in #40.

[codecov-io]

Codecov Report

Merging #41 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #41   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           1      1           
  Lines          92     94    +2     
=====================================
+ Hits           92     94    +2

Impacted Files	Coverage Δ
index.js	100% <100%> (ø)	⬆️

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[jorgebucaran]

@julien-f What do you think about the example I added to the docs? Could it be improved?

[julien-f]

Looks fine to me 🙂