Fix an error on README

[seratch]

Summary

This pull request just fixes a minor error in a code example on README.

Requirements (place an x in each [ ])

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[codecov]

Codecov Report

Merging #398 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #398   +/-   ##
=======================================
  Coverage   81.33%   81.33%           
=======================================
  Files           7        7           
  Lines         525      525           
  Branches      150      150           
=======================================
  Hits          427      427           
  Misses         70       70           
  Partials       28       28

---

Continue to review full report at Codecov.

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[codecov]

Codecov Report

Merging #398 into master will not change coverage by %.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #398   +/-   ##
=======================================
  Coverage   81.33%   81.33%           
=======================================
  Files           7        7           
  Lines         525      525           
  Branches      150      150           
=======================================
  Hits          427      427           
  Misses         70       70           
  Partials       28       28           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update a7c4db5...d3ec601. Read the comment docs.