Hello Martin,

At the moment, the comparison is massively out-of-date - as it seems to refer to doctest when it was less than half its current age, IIANM.

But be that as its may - I believe it is imperative, so as not to confuse people, to do the following:

1. Indicate the release version (or commit hash) used for each column of the comparison table.
2. Indicate the date the comparison was made (which may not be the date of the last editing of README.md)