Installation: simplify and use a Yaml file. Jupter-lab has been considered and...

Installation: simplify and use a Yaml file. Jupter-lab has been considered and discarded as it introduces many issues (table of contents is not working, currently up-to-date extensions are not compatible with up-to-date jupyter lab and so forth...).

README.md

@@ -34,13 +34,8 @@ Should the procedure described below not work at some point I invite you to chec
 * Create a new conda environment and activate it:
 
 ```
-conda create -n cling
-conda activate cling
-```
-
-* Install xeus-cling in this environment (and additional Jupyter extension to handle stuff like citations and table of contents).
-```
-conda install xeus-cling notebook jupyter_contrib_nbextensions -c QuantStack -c conda-forge
+conda env create -f environment.yml 
+conda activate formation_cpp_2020
 ```
 
 * Then you can run the notebook by going **into its root directory** (or internal links won't work...) in a terminal and typing:

environment.yml

+name: formation_cpp_2020
+channels:
+  - conda-forge
+dependencies:
+  - python>=3.7
+  - jupyter
+  - xeus-cling 
+  - notebook 
+  - jupyter_contrib_nbextensions
\ No newline at end of file