readme update

README.md

@@ -50,6 +50,7 @@ You will also need to have the following programs installed on your computer.
 	3. Use [ecoPCR](https://git.metabarcoding.org/obitools/ecopcr/wikis/home)
  to simulate an *in silico* PCR
 	4. Clean the database
+	5. (optionnal : only if you use [bash_swarm](https://gitlab.mbb.univ-montp2.fr/edna/bash_swarm) pipeline) Convert into STAMPA format
 
 * Run the script