Fix typo in permission for profiling

  <ul>

    <li>If you are using the {@link android.os.Debug} class,

     your application must have permission to write to external storage

     ({@link android.Manifest.permission#READ_EXTERNAL_STORAGE}). </li>

     ({@link android.Manifest.permission#WRITE_EXTERNAL_STORAGE}). </li>

    <li>If you are using DDMS:

      <ul>

        <li>Android 2.1 and earlier devices must