LU-930 doc: man page for lctl nodemap_set_sepol

LU-930 doc: man page for lctl nodemap_set_sepol

Man page for lctl nodemap_set_sepol.

Lustre-change: https://review.whamcloud.com/34084
Lustre-commit: 4813c6afbe77137facf4579f458d34d4dda40dd5

Test-Parameters: trivial
Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: I9e27aaa7d5653fcd6225a424bdbb920471b01555
Reviewed-on: https://review.whamcloud.com/34835
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>