Fix formatting in walkthrough

[coffeemakr]

In case you didn't already notice there is a small formatting error in the docs.

[codecov-io]

Current coverage is 99.69%

Merging #151 into master will not affect coverage as of 2f828ad

@@            master    #151   diff @@
======================================
  Files           15      15       
  Stmts         2659    2659       
  Branches         0       0       
  Methods          0       0       
======================================
  Hit           2651    2651       
  Partial          0       0       
  Missed           8       8       

Review entire Coverage Diff as of 2f828ad

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[meejah]

cool, thanks :)