[NEW] Headings for rows of tables

[Rob Beezer]

ou may now specify that the first column of a table ("tabular", really) contains
headings for the rows of your table. Consonant with good style, just the first
column. So use a @row-headers attribute on your "tabular", with values "yes"
or "no".

See The Guide for more, including some general updates in the vicinity.

Subsection 4.18.5: Table Columns
https://pretextbook.org/doc/guide/html/topic-tabular.html#subsection-83