Reference.md

@@ -142,12 +142,29 @@ graph TD;
 
 ```
 
-# Workflow manager
+# Workflow management
+
+We use [snakemake](https://snakemake.readthedocs.io/en/stable/), a workflow management system to create scalable and reproducible metabarcoding analysis.
+
 
 ## Environment
 
+
+Softwares and dependencies can be run directly using environments such as containers or package management system.
+
 ### Containers
 
+[![https://www.singularity-hub.org/static/simg/hosted-singularity--hub-%23e32929.svg](https://www.singularity-hub.org/static/img/hosted-singularity--hub-%23e32929.svg)](https://singularity-hub.org/collections/2878)
+
+
+We provide ready to run versions of [Singularity containers](https://www.sylabs.io/). All softwares you need to run the workflow have been installed into a container.
+
+To download this container :
+```
+singularity pull --name obitools.simg shub://Grelot/bioinfo_singularity_recipes:obitools
+```
+You will get a file named `obitools.simg`. Snakemake will need it to run softwares it contains.
+
 
 
 ### Conda