Minor documentation update to clarify the default behavior of the srun option

bug 327

doc/man/man1/srun.1

@@ -228,8 +228,9 @@ To ensure that distinct CPUs are allocated to each job step, use the
 
 If the job step allocation includes an allocation with a number of
 sockets, cores, or threads equal to the number of tasks to be started
-then the tasks will by default be bound to the appropriate resources.
-Disable this mode of operation by explicitly setting "-\-cpu\-bind=none".
+then the tasks will by default be bound to the appropriate resources (auto
+binding). Disable this mode of operation by explicitly setting
+"-\-cpu\-bind=none".
 
 Note that a job step can be allocated different numbers of CPUs on each node
 or be allocated CPUs not starting at location zero. Therefore one of the
@@ -253,7 +254,7 @@ Quietly bind before task runs (default)
 Verbosely report binding before task runs
 .TP
 .B no[ne]
-Do not bind tasks to CPUs (default)
+Do not bind tasks to CPUs (default unless auto binding is applied)
 .TP
 .B rank
 Automatically bind by task rank.