Fix link to config.json

[jmerle]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

It fixes a broken link in the readme.

• What is the current behavior? (You can also link to an open issue here)

The link in

Both strict and flexible typescript configurations available

no longer points to an existing file.

• What is the new behavior (if this is a feature change)?

The link points to an existing file.

• Other information:

Nope.

[codecov]

Codecov Report

Merging #212 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #212   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           9      9           
  Lines         261    261           
  Branches       39     39           
=====================================
  Hits          261    261

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[bitjson]

Thanks for the PR @jmerle! Merged 🚀

[jmerle]

I forgot I even created this PR, made it for Hacktoberfest 2019 I think, thanks for the merge!