comark/metrics/column-count · Give a ::stats table three columns, or two with tiles

A ::stats table has three columns: a name, the value before, and the value after. With tiles, it can also have two: a name and a value. A table with more or fewer columns is shown as written, without a change column or tiles, and a row with more or fewer cells has no change. Move other columns to a table of their own, or write ::stats{tiles} for a table of names and values.

Incorrect

::stats
| Metric | Before | After | Owner |
| --- | --- | --- | --- |
| Deploy time | 4.2 min | 3.1 min | Duck team |
::

lint-comark example.mdexample.md:1:1 comark/metrics/column-count::stats 1: its table has 4 columns, but needs 3: a name, a before, and an after value.Move other columns to a table of their own.✖ 1 problem

Correct

::stats
| Metric | Before | After |
| --- | --- | --- |
| Deploy time | 4.2 min | 3.1 min |
::

lint-comark example.md✔ No problems