remake observed biased confirmed CFR figure

- Second, the figure is a little confusing as the dashed lines are not included in the legend. I suggest re-making this figure with their data, and more clearly marking the predicted CFR with uncertainty shown as a shaded region.
- Third, it may be useful to annotate this figure for better understanding. E.g. annotate the period 1 -- 15 days where CFR is zero to indicate this is due to no reported deaths; annotate the middle section where CFR appears to be rising; annotate the final section where the estimate stabilises. All annotations should be short explanations of the observed trend.

_Originally posted by @pratikunterwegs in https://github.com/epiverse-trace/tutorials-middle/pull/1#discussion_r1502501780_