Remove errant bitly

[thomasrockhu]

fixes #128

Steve added this 5 years ago, I have no idea what it's supposed to actually point to now.

[codecov]

Codecov Report

Merging #220 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #220   +/-   ##
=======================================
  Coverage   84.25%   84.25%           
=======================================
  Files          23       23           
  Lines         381      381           
  Branches       95       95           
=======================================
  Hits          321      321           
  Misses         49       49           
  Partials       11       11           

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[drazisil-codecov]

Looks like the same way as we do now. https://travis-ci.org/github/pyca/cryptography/jobs/75080600#L443

I like the inline example better.