Fix typos in devstack/stack.sh

log to the the file => log to the file
pluggins => plugins

Change-Id: Iff5c54c39afb4398962bfe6a0500b1f011c75c8a
diff --git a/stack.sh b/stack.sh
index 639f72b..40f4813 100755
--- a/stack.sh
+++ b/stack.sh
@@ -431,7 +431,7 @@
 
 # Set up logging of screen windows
 # Set ``SCREEN_LOGDIR`` to turn on logging of screen windows to the
-# directory specified in ``SCREEN_LOGDIR``, we will log to the the file
+# directory specified in ``SCREEN_LOGDIR``, we will log to the file
 # ``screen-$SERVICE_NAME-$TIMESTAMP.log`` in that dir and have a link
 # ``screen-$SERVICE_NAME.log`` to the latest log file.
 # Logs are kept for as long specified in ``LOGDAYS``.
@@ -522,7 +522,7 @@
 # Clone all external plugins
 fetch_plugins
 
-# Plugin Phase 0: override_defaults - allow pluggins to override
+# Plugin Phase 0: override_defaults - allow plugins to override
 # defaults before other services are run
 run_phase override_defaults