docs: fix code block close tag

[erik-perri]

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

If yes, then include "BREAKING CHANGES:" in the first commit message body, followed by a description of what is breaking.

List any relevant issue numbers:

Description

The code block is not being closed properly so is not rendering right on Github.

[codecov-io]

Codecov Report

Merging #239 (19cb321) into master (3b2ed8a) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master      #239   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            3         3           
  Lines          111       111           
=========================================
  Hits           111       111           

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[shellscape]