LU-11871 doc: man page for lctl nodemap_set_fileset

LU-11871 doc: man page for lctl nodemap_set_fileset

Man page for lctl nodemap_set_fileset.

Lustre-change: https://review.whamcloud.com/34057
Lustre-commit: 76965ebc257ef1a090df2b21f107739f6471a9af

Test-Parameters: trivial
Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: Icce0b1558621bca84b14f76037a5000002855881
Reviewed-on: https://review.whamcloud.com/34834
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Joseph Gmitter <jgmitter@whamcloud.com>
Reviewed-by: James Nunez <jnunez@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>