Lots of broken links

[aurora]

There are many broken links in the bootcamp texts, e.g.: Unit 3, Lesson 4 - the PipeTo sample code. Of course, I can look up the code in the history of the akkadotnet-code-sample repository, but I wonder what it means that the sample code has been removed from the master branch - is it no longer relevant? If so, you should update the bootcamp accordingly. Thanks anyway for the great work.