adding layout references

cmd/README.md

@@ -7,3 +7,7 @@ The directory name for each application should match the name of the executable
 Don't put a lot of code in the application directory. If you think the code can be imported and used in other projects, then it should live in the `/pkg` directory. If the code is not reusable or if you don't want others to reuse it, put that code in the `/internal` directory. You'll be surprised what others will do, so be explicit about your intentions!
 
 It's common to have a small `main` function that imports and invokes the code from the `/internal` and `/pkg` directories and nothing else.
+
+Examples:
+
+* https://github.com/heptio/ark/tree/master/cmd