Added text about environment.yml

Author: jeipollack

docs/source/installation.md

@@ -5,6 +5,8 @@ WaveDiff is a software written in Python and uses the [TensorFlow](https://www.t
 
 Note: You may want to set up a dedicated Python environment for running WaveDiff using e.g. [Conda](https://docs.conda.io/en/latest/).  You can use the minimal installer [Miniconda](https://docs.conda.io/projects/miniconda/en/latest/) to set up the environment in which we run the command below to install the subset of packages needed for running WaveDiff.
 
+In the [WaveDiff repository](https://github.com/CosmoStat/wf-psf.git), we provide in the file `environment.yml` the specific environment used in the testing of `WaveDiff`. We recommend users to work with this environment for the current release. 
+
 ## Installation Steps
 
 Clone the repository: