scale of y axis in README plot is unclear

[simonpcouch]

From @topepo:

in the readme, does the last plot (rss usage) have log units on the y-axis? It looks like it but the code doesn't show that.

bench automatically applies bench::scale_y_bench_bytes under the hood, but may be worth just added that line explicitly so folks know where it comes from.

syrup/README.md

Lines 167 to 175 in dc2b51d

	res_mem %>%
	filter(ppid == worker_ppid | pid == worker_ppid) %>%
	ggplot() +
	aes(x = id, y = rss, group = pid) +
	geom_line() +
	scale_x_continuous(breaks = 1:max(res_mem$id))
	```
	<img src="man/figures/README-plot-mem-1.png" width="100%" />

[simonpcouch]

Closing in favor of r-lib/bench#144.