add emacs shell-script tagging

for files that don't start with a #! or end in .sh, the added tags
are nice for emacs users to automatically switch to the right mode.

Change-Id: If4b93e106191bc744ccad8420cef20e751cdf902
diff --git a/lib/baremetal b/lib/baremetal
index 5326dd1..24cce9f 100644
--- a/lib/baremetal
+++ b/lib/baremetal
@@ -434,3 +434,7 @@
 
 # Restore xtrace
 $XTRACE
+
+# Local variables:
+# mode: shell-script
+# End: