Update typo in data-import.qmd (hadley#1570)

"There are two main alternative:"

added an "s"

Author: 0solarfox0

data-import.qmd

@@ -463,7 +463,7 @@ read_csv("students-2.csv")
 ```
 
 This makes CSVs a little unreliable for caching interim results---you need to recreate the column specification every time you load in.
-There are two main alternative:
+There are two main alternatives:
 
 1.  `write_rds()` and `read_rds()` are uniform wrappers around the base functions `readRDS()` and `saveRDS()`.
     These store data in R's custom binary format called RDS.