fix typo

chapters/split-plot-design.qmd

@@ -1,7 +1,7 @@
 # Split Plot Design
 
 ```{r, include=FALSE}
-source(here::here("settings.R"))
+source(here::here("settings.r"))
 ```
 
 Split-plot design is frequently used for factorial experiments. Such design may incorporate one or more of the completely randomized (CRD), completely randomized block (RCBD), and Latin square designs. The main principle is that there are whole plots or whole units, to which the levels of one or more factors are applied. Thus each whole plot becomes a block for the subplot treatments.