change axis font ggplot2 code example

Example: ggplot increase label font size

d <- data.frame(x=gl(10, 1, 10, labels=paste("long text label ", letters[1:10])), y=rnorm(10))
ggplot(d, aes(x=x, y=y)) + geom_point() +
theme(text = element_text(size=20))