Fix a number of the following issues in man4:

Fix a number of the following issues in man4:
- Inconsistencies in .Dd like abbreviated month names,
"th" after numbers, or leading zeros
- No line breaks after a sentence stop
- Whitespace at the end of the line
- Use macros for BSD OS names instead of hardcoded names
- CAVEATS instead of CAVEAT in section name

No actual content change in terms of additions were made, so
no bump of the .Dd for these man pages.
All of these issues were found and fixed by Gordon Bergling.

Submitted by:	    gbergling_gmail.com
Approved by:	    bcr
Differential Revision:	https://reviews.freebsd.org/D24648