add missing backtick

_episodes_rmd/02-func-R.Rmd

@@ -123,7 +123,7 @@ Real-life functions will usually be larger than the ones shown here--typically h
 > e.g. `x <- c("A", "B", "C")` creates a vector `x` with three elements.
 > Furthermore, we can extend that vector again using `c`, e.g. `y <- c(x, "D")` creates a vector `y` with four elements.
 > Write a function called `fence` that takes two vectors as arguments, called
-> original` and `wrapper`, and returns a new vector that has the wrapper vector
+> `original` and `wrapper`, and returns a new vector that has the wrapper vector
 > at the beginning and end of the original:
 >
 > ```{r, echo=-1}