Removed chunk refering to wrong section (#619)

Author: MichalLauer

scaling-testing.Rmd

@@ -755,5 +755,3 @@ There are three basic options
 This chapter has showed you how to organise your app into a package so that you can take advantage of the powerful tools provided by the testthat package.
 If you've never made a package before, this can seem overwhelming, but as you've seen, a package is just a simple set of conventions that you can readily adapt for a Shiny app.
 This requires a little up front work, but unlocks a big payoff: the ability to automate tests radically increases your ability to write complex apps.
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-In the next chapter you'll learn out how to figure out what's making your apps slow, and some techniques for making them faster.