If you know how to fix a problem in a man page (if not, look here), then send a patch, and make sure that you:
The above is the minimum needed to ensure that there's some chance I'll see the patch. (If you did that, and I do not respond, then ping the mail thread, "replying to all". Unfortunately, I get more mail than I can sometimes deal with, and things do get lost.)
To make your patch even more useful, please note the following points:
[patch] shmop.2: Add "(void *)" cast to RETURN VALUE
.\" commit <40-character-git-hash>Doing so can be useful to help verify details of the patch, or for later historical reference.
[patch] tcp.7: tfix
If the man page that you want to patch is not in the tarball or Git repository, that's because it comes from a package other than man-pages; in that case, you should look here.