chore : upd readme

README.md

@@ -16,12 +16,14 @@ So far be sure to have the correct requirements to use this library
 
 You will need to install first the ``aidge_core`` library before installing ``aidge_backend_cpu``.
 
-If you have set a custom install path for the ``aidge_core`` library, make sure to use the same one here.
-
 Then run in your python environnement :
 ``` bash
 pip install . -v
 ```
+> **TIPS :** Use environment variables to change compilation options :
+> - `AIDGE_INSTALL` : to set the installation folder. Defaults to /usr/local/lib. :warning: This path must be identical to aidge_core install path.
+> - `AIDGE_PYTHON_BUILD_TYPE` : to set the compilation mode to **Debug** or **Release** 
+> - `AIDGE_BUILD_GEN` : to set the build backend with 
 
 ## Standard C++ Compilation