chore(config): Add union merge strategy for README.md

[paulmolluzzo]

What:
With this inclusion git will attempt to keep multiple changes to a README to avoid conflicts

Why:
This is something I learned about here. That project had lots of changes to the README, and in glamorous the all-contributors might cause unnecessary conflicts. This could be nice to have and avoid merging/rebasing a PR.

How:
Small change in the .gitattributes file.

More info is available here: isaacs/github#487

[codecov-io]

Codecov Report

Merging #30 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master    #30   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           2      2           
  Lines          60     60           
  Branches        9      9           
=====================================
  Hits           60     60

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[kentcdodds]

Cool! I'm willing to give this a shot! If it works out well, then I'll add it to my generator. Thanks!

[paulmolluzzo]

I'm wondering if we should also add .all-contributorsrc as well. It's another file that will get mostly additions where we'll want to keep both. Look at the conflicting files for #27 as an example.

Could be worth waiting on though. I haven't used it on a js/json file before and it might break syntax. IDK.

[kentcdodds]

Yeah, I still don't really understand what this does 😅

[paulmolluzzo]

If there are two additions on the same line it'll keep both additions.

[kentcdodds]

Ah, yeah, better not then...