fix: exclamation mark in underline buffer

src/markdown.rs

@@ -272,6 +272,9 @@ fn parse_underline_line(output: &mut String, buffer: &mut String, line: &str) {
                     is_open = false;
                     close_1 = false;
                     continue;
+                } else if is_open {
+                    buffer.push(char);
+                    continue;
                 }
 
                 // open