[Pharo-dev] [updated Pharo by example] new chapter to review

[stepharo]

https://ci.inria.fr/pharo-contribution/view/Books/job/UpdatedPharoByExample/lastSuccessfulBuild/artifact/book-result/Streams/Streams.pdf
I hope that in Pharo 6 we will migrate to Xstreams but for now this 
chapter should be ok.

Stef