doc: add forgotten dependancies in the readme

README.md

@@ -15,7 +15,10 @@ The idea behind it is to keep the *logic* of user submissions rather than the ex
 
 
 ## Usage
-You need python3 installed on your machine. 
+Requirements:
+- python3
+- [networkx](https://github.com/networkx/networkx) (optional, for the graph outputs): `pip3 install networkx`
+- [pytest](https://pytest.org/) (optional, for the tests): `pip3 install pytest`
 
 To run the session decomposition on the workload `workloads/example.swf` illustrated above, with "Arrival" delimitation approach and a threshold of 60 minutes:
 
@@ -26,9 +29,4 @@ python3 swf2sessions.py -at 60 workloads/example.swf out/
 For more documentation, see: `python3 swf2sessions.py -h`
 
 ## Tests
-Some integration tests have been written for this script, and are stored in the `test/` folder. To run them on your machine, you need to install pytest and launch it at the root of the project:
-
-```terminal
-pip3 install pytest
-pytest
-```
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+Some integration tests have been written for this script, and are stored in the `test/` folder. To run them on your machine, just type `pytest` at the root of the project.
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