[kroplabeskidu]

What kind of change does this PR introduce?

Feature. Fixes #1657

doc.table({ headerRows: 1, data });

The first rows are drawn again at the top of each new page, and the next row goes below them. If that row wouldn't fit below the header, the header is skipped on that page. In a structured table the repeated rows are marked as pagination artifacts, so they aren't added to the structure again.

Compared with similar APIs:

Library	API
pdfmake	headerRows: 1
ReportLab	repeatRows=1
Prawn	table(data, header: true)
jsPDF-AutoTable	showHead: 'everyPage'

I used headerRows from pdfmake, since it is a JS library with the same data shape, and a count also covers several header rows.

I checked a 3 page table with pdf.js, with and without structParent: every page starts with the header and the next row sits below it.

A header at the very bottom of a page can still be left alone there, and a rowSpan reaching past the header rows isn't repeated.

Checklist:

• Unit Tests
• Documentation
• Update CHANGELOG.md
• Ready to be merged