docs(backend): dry run project for backend

docs/src/backend/00_backend.md

@@ -9,3 +9,10 @@ The goal of this part of the workshop is to create a simple API that will be use
 - [Shuttle](https://www.shuttle.rs/)
 
 Take the time to read the documentation of each of these tools and frameworks to learn more.
+
+## Guide
+
+If you get lost during the workshop, you can always refer to:
+- the workshop conductors
+- the [workshop GitHub repository](https://github.com/bcnrust/devbcn-workshop) which contains the final code with tests, mocks, memory database, etc.
+- the [dry-run workshop GitHub repository](https://github.com/BcnRust/devbcn-workshop-dryrun/commits/master): each commit corresponds to a step of the workshop. You will see that some sections will instruct you to commit your code. You can always refer to this repository to see what the code should look like at that point.