Reorganize zfs(8) man page into sections

Most subcommands got their own manpages (e.g. create). Some related
commands grouped into a single manpage and symlinks created (e.g. set, 
get, and inherit). I did this when topics were either too short to 
warrant their own file or so interrelated that a user would want to
refer between commands in the same file.

Corrected .Sx internal references to .Xr cross refs; lots of .Sx 
references from when text was all in zfs.8 needed to be changed to 
.Xr zfs-$SUBCOMMAND 8 cross references.

Divided subcommand list in zfs(8) into sections of related 
functionality. This required writing new descriptions for some 
commands.

Preserved ".Os Linux", `.Os` macro parsing behavior differs between 
mandoc from the "BSD" mandoc package (available on Ubuntu) and man 
from Ubuntu's man-db package, which calls groff to format the manpages.

Groff handles the `.Os` macro differently and wrongly, defaulting 
it to "BSD" in `/usr/share/groff/*/tmac/mdoc/doc-common`, instead of
getting the default from `uname`.

A future set of changes will introduce build-time preprocessing of
manpages for platform-specific documentation and can insert the
correct operating system name.

Added SEE ALSO sections, the newly-divided zfs-*.8 subcommand man
pages needed their own SEE ALSO sections pointing to related
subcommands and, in some cases, documentation from other packages
(e.g. zfs-share.8).

Reviewed-by: Matt Ahrens <[email protected]>
Reviewed-by: Kjeld Schouten <[email protected]>
Reviewed-by: Sean Eric Fagan <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Ross Williams <[email protected]>
Closes #9559 

1 files changed, 1 insertions, 0 deletions

diff --git a/man/man8/zfs-unmount.8 b/man/man8/zfs-unmount.8
new file mode 120000
index 000000000..be0d9dbf6
--- /dev/null
+++ b/man/man8/zfs-unmount.8
@@ -0,0 +1 @@
+zfs-mount.8
\ No newline at end of file