Improved main README

Mostly documentation of how to build docker.

README.md

@@ -5,7 +5,7 @@ It is composed of the following folders:
 * `sources`: contains all code sources: `libnix` (helper library) `Vascularization` (generate geometry direct problem) and `VascularizationInverse` (inverse problem)
 * `docker`: contains `Dockerfile` that automatically builds the code in a controled environement.
 
-## How to build and run the code
+## Build the code
 
 It is recommended to use the provided `Dockerfile` that will create a Ubuntu 22.04 environment with the necessary dependencies installed.
 The `Dockerfile` will also compile all sources and produce executables for each of the code mentioned on previous section.
@@ -22,6 +22,9 @@ To run the created docker image:
 docker run -i -t --network host dce-mri
 ```
 
+The `Dockerfile` will automatically download the latest sources on the [gitlab repository](https://gitlab.inria.fr/jdichamp/dyna-imaging-mod).
+The different code executable and libraries will be built in their dedicated folders: `libnix`, `Vascularization`, `VascularizationInverse`.
+
 ## Simulation examples
 ### Direct problem
 Inside the docker container:
@@ -60,4 +63,4 @@ do
 done
 
 $COMMAND
-```
\ No newline at end of file
+```