Parse any spreadsheet range into a table for GitHub, Obsidian, etc.
Expects a header row.
/* Google Apps Script */
/**
 * Select any spreadsheet range, and return a string-parsed table for GitHub, Obsidian, etc. 
 * Note:  Obsidian requires a prefixed empty space for the header row, if the first cell is blank. 
 * @param {Array<Array>} array2d - The source range.