Added run notes to TODO.

examples/todo/README.md

@@ -1,4 +1,16 @@
 Rocket Todo Example
 ===================
 
-Fill this in on instructions for how to create the DB, etc.
+Before running this example, you'll need to ensure there's a database file
+present. You can do this with Diesel.
+
+Running migration with Diesel
+-----------------------------
+
+Just run the following commands in your shell:
+
+```
+cargo install diesel_cli # installs the diesel CLI tools
+DATABASE_URL=db/db.sql diesel migration run # create db/db.sql
+```
+