dd behaviour not in documentation (manpage)

Description:

An instance of `dd` running with `bs=1M of=/dev/null` inappropriately reports the block size. This is a documented and known behavior of `dd` and can be mended by using `iflag=fullblock` on the output side. However our documentation for the program seems to be lacking this section of the source documentation.

Additional info:

• package version(s): coreutils 9.4-2 linux 6.6.4.arch1-1
• config and/or log files: NA
• link to upstream bug report, if any: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=68216

Steps to reproduce:

1. Run this example: dd if=/dev/zero bs=1M count=1 | dd bs=1M of=/dev/null
2. Notice the second dd command returns a count of records based on the default behavior of bs=512
3. Try again with iflag=fullblock on the output side to see the intended record count.