fix(task): handle multiline descriptions properly (#27069)

Closes https://github.com/denoland/deno/issues/27049

cli/tools/task.rs

@@ -721,11 +721,9 @@ fn print_available_tasks(
     )?;
     if let Some(description) = &desc.task.description {
       let slash_slash = colors::italic_gray("//");
-      writeln!(
+      for line in description.split('\n') {
-        writer,
+        writeln!(writer, "    {slash_slash} {}", colors::italic_gray(line))?;
-        "    {slash_slash} {}",
+      }
-        colors::italic_gray(description)
-      )?;
     }
     writeln!(writer, "    {}", desc.task.command)?;
     if !desc.task.dependencies.is_empty() {

tests/specs/task/description/deno.json

@@ -3,6 +3,10 @@
     "echo_emoji": {
       "description": "This is some task",
       "command": "echo 1"
+    },
+    "multiline_description": {
+      "description": "This is a multiline\ndescription",
+      "command": "echo 2"
     }
   }
 }

tests/specs/task/description/main.out

@@ -2,3 +2,7 @@ Available tasks:
 - echo_emoji
     // This is some task
     echo 1
+- multiline_description
+    // This is a multiline
+    // description
+    echo 2