Update r-basics-with-tabular-data.md

Replace broken link with perma.cc.

Author: anisa-hawes

en/lessons/r-basics-with-tabular-data.md

@@ -110,7 +110,7 @@ R can do more than just simple arithmetic. You can create [objects](https://en.w
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-R is case sensitive, so be careful that you use the same notation when you use the variables you have assigned (or named) in other actions. See Rasmus Bååth's article, [The State of Naming Conventions in R](https://journal.r-project.org/archive/2012-2/RJournal_2012-2_Baaaath.pdf), for more information on how to best name variables.
+R is case sensitive, so be careful that you use the same notation when you use the variables you have assigned (or named) in other actions. See Rasmus Bååth's article, [The State of Naming Conventions in R](https://perma.cc/ME6W-JZJQ), for more information on how to best name variables.
 
 To remove a variable from the console, type `rm()` with the variable you want to get rid of inside the brackets, and press *Enter*. To see all of the variables you have assigned, type `ls()` into the console and press *Enter* - this will help you avoid using the same name for multiple variables. This is also important because R stores all of the objects you create in its memory, so even if you cannot see a variable named `x` in the console, it may have been created before and you could accidentally overwrite it when assigning another variable.