Update to 1.004

Upstream changes:
1.004  2020-09-26
        - No code changes since 1.003, just documentation improvements
        - New example file: detect-encoding.pl

1.003  2015-09-26 Trial Release
        - Do not use incomplete quoted attribute values in find_charset_in.
          If we reach the end of the string without finding the closing quote,
          terminate processing instead of using whatever we did collect as
          the attribute's value.
        - Add tests for the $bytes_to_check configuration variable (GitHub#1)

1.002  2015-09-19 Trial Release
        - Add $bytes_to_check configuration variable (GitHub#1)

(wen)