docs: add new ext4 superblock time extension fields

The superblock timestamp fields were enlarged by u8 to be 40 bits wide.
Update the documentation to reflect this.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Documentation/filesystems/ext4/ondisk/super.rst

@@ -442,8 +442,36 @@ The ext4 superblock is laid out as follows in
      - Checksum seed used for metadata\_csum calculations. This value is
        crc32c(~0, $orig\_fs\_uuid).
    * - 0x274
-     - \_\_le32
-     - s\_reserved[98]
+     - \_\_u8
+     - s\_wtime_hi
+     - Upper 8 bits of the s_wtime field.
+   * - 0x275
+     - \_\_u8
+     - s\_wtime_hi
+     - Upper 8 bits of the s_mtime field.
+   * - 0x276
+     - \_\_u8
+     - s\_mkfs_time_hi
+     - Upper 8 bits of the s_mkfs_time field.
+   * - 0x277
+     - \_\_u8
+     - s\_lastcheck_hi
+     - Upper 8 bits of the s_lastcheck_hi field.
+   * - 0x278
+     - \_\_u8
+     - s\_first_error_time_hi
+     - Upper 8 bits of the s_first_error_time_hi field.
+   * - 0x279
+     - \_\_u8
+     - s\_last_error_time_hi
+     - Upper 8 bits of the s_last_error_time_hi field.
+   * - 0x27A
+     - \_\_u8[2]
+     - s\_pad
+     - Zero padding.
+   * - 0x27C
+     - \_\_le32
+     - s\_reserved[96]
      - Padding to the end of the block.
    * - 0x3FC
      - \_\_le32