Bug #47489 Sample configuration file erroneous comment

Description:
Bug#44470 fixed the support-files/my-innodb-heavy-4G.cnf.sh sample
configuration file to use innodb_{read,write}_io_threads instead
of innodb_file_io_threads, as follows:

# Number of IO threads to use for async IO operations. This value is
# hardcoded to 8 on Unix, but on Windows disk I/O may benefit from a
# larger number.
innodb_write_io_threads = 8
innodb_read_io_threads = 8

However, the comment is now in error because the value is no longer
hardcoded on Unix and the benefit may no longer be limited only to
Windows.  The comment should be corrected.

Another issue is that this part of the file sets both variables to
the Summit defaults of 8. Perhaps it should use the InnoDB Plugin
defaults of 4. (This is not necessarily a bug, I am just point it
out because the Summit and Plugin defaults differ.)

How to repeat:
By inspection.

Thank you for the problem report. Verified by code review.