What markup should be used to turn the first row into a table header?
+-------+----------+-------------------------------------------------+
| Bits | Field | Description |
| | Name | |
+-------+----------+-------------------------------------------------+
| 31:28 | FORMAT | Indicates size of data type in buffer in bytes |
| | | Indicates size of data type in buffer in bytes |
| | | Indicates size of data type in buffer in bytes |
| | | Indicates size of data type in buffer in bytes |
+-------+----------+-------------------------------------------------+
That appears to be Pandoc's grid_tables. The header should be separated from the body by =, like this:
+-------+----------+-------------------------------------------------+
| Bits | Field | Description |
| | Name | |
+=======+==========+=================================================+
| 31:28 | FORMAT | Indicates size of data type in buffer in bytes |
| | | Indicates size of data type in buffer in bytes |
| | | Indicates size of data type in buffer in bytes |
| | | Indicates size of data type in buffer in bytes |
+-------+----------+-------------------------------------------------+