Add indication of type of vertical scale to downloadable graphs

[marcopiani]

Hi,

while many people take screen grabs of the OWID graphs, I prefer to download/copy the graphs as provided by the download option.

One issue is that those graphs miss the indication of which vertical scale is used. The reader may get that from looking at the ticks/gridlines, but it is not made explicit.

Perhaps it might be easy to add information about the vertical scale used in the downloadable graph?

A low-hanging fruit is adding that piece of information to the subtitle, as simple text. Below an example (second image) done by modifying one .svg file with a simple text editor (extra details about the modification to respect the license).

As usual, thank you for your work and for the consideration you might give to the issue.

Marco