Clarify the comments in the codelab.

Jacob had some good questions.  Help the next person.

Change-Id: I03de05e0930c95ba46129917d39a71b2f077208e
diff --git a/frc971/codelab/basic.h b/frc971/codelab/basic.h
index 944048f..b75a87f 100644
--- a/frc971/codelab/basic.h
+++ b/frc971/codelab/basic.h
@@ -15,6 +15,9 @@
 // This codelab helps build basic knowledge of how to use 971 control loop
 // primatives.
 //
+// For flatbuffers background, we recommend checking out
+// https://google.github.io/flatbuffers/flatbuffers_guide_tutorial.html
+//
 // The meat of the task is to make the tests pass.
 //
 // Run the tests with: