fix default branch

README.md

@@ -100,8 +100,8 @@ To set up the development environment, run:
 
  1. get the sources
  	<pre>
-	git clone git@gitlab.irisa.fr:charly.maupetit/rails-allgo.git
-	git clone git@gitlab.irisa.fr:sebastien.campion/allgo.git
+	git clone git@gitlab.irisa.fr:charly.maupetit/rails-allgo.git -b docker
+	git clone git@gitlab.irisa.fr:sebastien.campion/allgo.git -b docker
 	cd allgo
 	</pre>
 	**Note:** the *allgo* repository has a symbolic link to the