man: fix typos in MPI_Info_get_{nkeys,nthkey}

Thanks Nicolas Joly for the patch

(cherry picked from commit 98f6269)

Signed-off-by: Gilles Gouaillardet <[email protected]>

Author: ggouaillardet

ompi/mpi/man/man3/MPI_Info_get_nkeys.3in

@@ -60,6 +60,6 @@ MPI_Info_get
 .br
 MPI_Info_get_nthkey
 .br
-MPI_Info_get_valueln
+MPI_Info_get_valuelen
 .br
 

ompi/mpi/man/man3/MPI_Info_get_nthkey.3in

@@ -65,6 +65,6 @@ MPI_Info_get
 .br
 MPI_Info_get_nkeys
 .br
-MPI_Info_get_valueln
+MPI_Info_get_valuelen
 .br