Replace ZFS on Linux references with OpenZFS

This change updates the documentation to refer to the project
as OpenZFS instead ZFS on Linux.  Web links have been updated
to refer to https://github.com/openzfs/zfs.  The extraneous
zfsonlinux.org web links in the ZED and SPL sources have been
dropped.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #11007

lib/libzfsbootenv/libzfsbootenv.pc.in

@@ -6,7 +6,7 @@ includedir=@includedir@
 Name: libzfsbootenv
 Description: LibZFSBootENV library
 Version: @VERSION@
-URL: https://zfsonlinux.org
+URL: https://github.com/openzfs/zfs
 Requires: libzfs libnvpair
 Cflags: -I${includedir}
 Libs: -L${libdir} -lzfsbootenv

lib/libzutil/os/linux/zutil_import_os.c

@@ -813,9 +813,9 @@ update_vdev_config_dev_strs(nvlist_t *nv)
 	 *	env ZFS_VDEV_DEVID_OPT_OUT=YES zpool import dozer
 	 *
 	 * explanation:
-	 * Older ZFS on Linux implementations had issues when attempting to
-	 * display pool config VDEV names if a "devid" NVP value is present
-	 * in the pool's config.
+	 * Older OpenZFS implementations had issues when attempting to
+	 * display pool config VDEV names if a "devid" NVP value is
+	 * present in the pool's config.
 	 *
 	 * For example, a pool that originated on illumos platform would
 	 * have a devid value in the config and "zpool status" would fail