Update 0.prep.md

add ggplot2 for later lessons

docs/0.prep.md

@@ -23,6 +23,7 @@ The data set, and any inference that is generated from it, is not our primary in
     library(purrr)
     library(tidyr)
     library(tibble)
+    library(ggplot2)
 
     asv <- read.delim("https://raw.githubusercontent.com/GenomicsAotearoa/Intermediate-R/main/tables/asv_table.tsv")
     env <- read.delim("https://raw.githubusercontent.com/GenomicsAotearoa/Intermediate-R/main/tables/env_table.tsv")