clean up screen and tail_log references

Change-Id: I6bcfa09931ed1f70e071ccb16688c15c7ef2898f
diff --git a/lib/dstat b/lib/dstat
index 982b703..fe38d75 100644
--- a/lib/dstat
+++ b/lib/dstat
@@ -16,7 +16,7 @@
 _XTRACE_DSTAT=$(set +o | grep xtrace)
 set +o xtrace
 
-# start_dstat() - Start running processes, including screen
+# start_dstat() - Start running processes
 function start_dstat {
     # A better kind of sysstat, with the top process per time slice
     run_process dstat "$TOP_DIR/tools/dstat.sh $LOGDIR"