added to help-mpirun.txt a topic named prte-launch-failed, an error messsage about how we failed to launch the user's application

Signed-off-by: Gerardo Garcia <gagarc07@louisville.edu>

Author: Gerardo Garcia

ompi/tools/mpirun/help-mpirun.txt

@@ -14,6 +14,10 @@
 Open MPI's mpirun command was unable to find an underlying prterun
 command to execute.  Consider setting the OMPI_PRTERUN environment
 variable to help mpirun find the correct underlying prterun.
+[prte-launch-failed]
+Open MPI's mpirun command was unable to launch the user's application 
+using the prterun command. This may indicate an issue with the prterun
+environment or incorrect configuration.
 [prterun-exec-failed]
 Open MPI's mpirun command could not execute the underlying prterun
 command.  The prterun command we tried to execute and the error