docs(parser): clarify why delimiter detection is needed

Unicode │ (U+2502) and ASCII | are different bytes, so splitting
on the wrong one produces no split at all.

src/parser.ts

@@ -23,7 +23,7 @@ function isDataRow(line: string): boolean {
 function splitCells(line: string): string[] {
   const trimmed = line.trim();
 
-  // Determine which delimiter is used
+  // Unicode │ (U+2502) and ASCII | are different bytes — split on the right one
   const delimiter = trimmed.includes("│") ? "│" : "|";
 
   const parts = trimmed.split(delimiter);