fix(docs): show vertically divided grid in grid layout

[fspinnenhirn]

a typo in GridLayout prevents the vertical grid dividers to display

[welcome]

💖 Thanks for opening this pull request! 💖

Here is a list of things that will help get it across the finish line:

• Run yarn lint locally to catch formatting errors. This will fix some errors automatically, commit and push any changes.
• Run yarn test locally to catch errors. This ensures all components still behave as they should.
• Run yarn start to run the doc site locally and try a few pages, ensuring everything is in good working order.
• Include tests when adding/changing behavior.

We get a lot of pull requests on this repo, so please be patient and we will get back to you as soon as we can.

[codecov-io]

Codecov Report

Merging #2677 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2677   +/-   ##
=======================================
  Coverage   99.74%   99.74%           
=======================================
  Files         160      160           
  Lines        2751     2751           
=======================================
  Hits         2744     2744           
  Misses          7        7

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[welcome]

Congrats on merging your first pull request! 🎉🎉🎉

[levithomason]

Released in semantic-ui-react@0.79.1.