brillo: Update documentation to run unittests.

Update test_droid.md with directions on how to run unittests.

BUG=none
TEST=none

Change-Id: Ic9d851f7e6cff32132212c6428c661c630a88bcc
Reviewed-on: https://chromium-review.googlesource.com/328829
Commit-Ready: Ralph Nathan <ralphnathan@chromium.org>
Tested-by: Ralph Nathan <ralphnathan@chromium.org>
Reviewed-by: Christopher Wiley <wiley@chromium.org>
diff --git a/docs/test-droid.md b/docs/test-droid.md
index 8e134e4..e61b383 100644
--- a/docs/test-droid.md
+++ b/docs/test-droid.md
@@ -122,7 +122,13 @@
 Be sure to run pylint on every file you touch:
 
 ```
-$ ./utils/run_pylint.py <file name>
+ $ ./utils/run_pylint.py <file name>
+```
+
+Run autotest unittests:
+
+```
+ $ utils/unittest_suite.py
 ```
 
 Then upload your commit for review: