Read a GFM pipe table's short rows, rows without a pipe and one column in portableMarkdownToAdf

spec/flavour.md

@@ -365,13 +365,15 @@ indentation.
 Cells split on unescaped `|` before inline parsing — `\|` stays in the cell text, and the
 inline layer's ordinary CommonMark escaping yields the pipe; each cell is the inline content of
 one paragraph, trimmed; canonical form pads cells with single spaces and ends rows with `|`
-(optional in input). Named errors: a delimiter or body row whose cell count differs from the
-header's, and, in `losslessMarkdownToAdf`, an alignment colon in the delimiter row — ADF holds no
-column alignment. In a pipe cell a hard break is `!adf:hardBreak{}` and a literal `|` is `\|`; a
+(optional in input). Named errors: a delimiter row whose cell count differs from the header's,
+a body row holding more cells than the header, and, in `losslessMarkdownToAdf`, a body row
+holding fewer cells and an alignment colon in the delimiter row — ADF holds no column alignment. In a pipe cell a hard break is `!adf:hardBreak{}` and a literal `|` is `\|`; a
 `|` inside a quoted attribute value is already `\u007c`, so the split never reaches it.
-`portableMarkdownToAdf` reads GFM's table: any row may drop its leading `|`, a body row continues
-the table while it holds a `|` and opens no other block, and an alignment colon is read and its
-alignment dropped.
+`portableMarkdownToAdf` reads GFM's table: any row may drop its leading `|`, a header over a
+delimiter row of one cell reads as a one-column table (`a |` over `--- |`), a body row continues
+the table until a blank line or a line opening another block, a body row holding fewer cells is
+padded with empty cells, a line holding no `|` is a body row of one cell, and an alignment colon is
+read and its alignment dropped.
 
 The directive form nests cells as containers of block content inside `tableRow` containers: