Add destination-path argument allowing overriding destination

[romainbou]

Add "destination-path" option to allow picking the destination of all the generated readme files.

This allows saving all the documentation in a subfolder like docs inside a repository.
Example goreadme -import-path=. -destination-path=docs/README.md
Will generate docs/README.md instead of README.md

[codecov]

Codecov Report

Merging #97 (5381a31) into master (7e9b8ca) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #97   +/-   ##
=======================================
  Coverage   69.51%   69.51%           
=======================================
  Files           3        3           
  Lines          82       82           
=======================================
  Hits           57       57           
  Misses         15       15           
  Partials       10       10           

Impacted Files	Coverage Δ
goreadme.go	67.34% <ø> (ø)

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[posener]

Hey, you can actually set the output path: env 'readme-file=docs/readme.md' goreadme, or with the readme-file argument for the Github action.

In the PR, you also created the parent directory, which we can add in any case.

Does that work for you?