[Docs] Update contributors link in CONTRIBUTING.md

[michaeljaltamirano]

Summary

It seems Github may have changed its Contributors URL since this was initially set up. The current href directs you to https://github.com/gregberge/svgr/blob/master/graphs/contributors, which is a broken page. The functioning page is https://github.com/gregberge/svgr/graphs/contributors, so I've inlined it in the href.

Test plan

Functionality on master breaks: https://github.com/gregberge/svgr/blob/master/CONTRIBUTING.md#credits

Functionality on fix branch works: https://github.com/michaeljaltamirano/svgr/blob/docs/update-contributors-link/CONTRIBUTING.md#credits

[vercel]

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[codecov]

Codecov Report

Merging #394 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #394   +/-   ##
=======================================
  Coverage   85.52%   85.52%           
=======================================
  Files          30       30           
  Lines         518      518           
  Branches      142      142           
=======================================
  Hits          443      443           
  Misses         62       62           
  Partials       13       13

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[gregberge]

Thanks