Better naming of the makefile rule

Makefile

 ressources-md:
-	for i in module1/ressources module2/ressources module3/ressources \
+	for i in module1/ressources module2/ressources module2/slides module3/ressources \
 	    module4/ressources; do \
-	     make -C $$i; \
+	     make -C $$i ressources-md; \
 	done

module1/ressources/Makefile

-all: introduction_to_markdown.md
+ressources-md: introduction_to_markdown.md introduction_to_markdown_fr.md
 
 include ../../Makefile.ressources

module2/ressources/Makefile

-all: emacs_orgmode.md emacs_orgmode_fr.md jupyter.md jupyter_fr.md maintaining_a_journal.md maintaining_a_journal_fr.md gitlab.md gitlab_fr.md rstudio.md rstudio_fr.md orgmode_examples/README.md orgmode_examples/README_fr.md
+ressources-md: emacs_orgmode.md emacs_orgmode_fr.md jupyter.md jupyter_fr.md maintaining_a_journal.md maintaining_a_journal_fr.md gitlab.md gitlab_fr.md rstudio.md rstudio_fr.md orgmode_examples/README.md orgmode_examples/README_fr.md
 
 include ../../Makefile.ressources
 

module3/ressources/Makefile

-all:
+resources-md:
 
 include ../../Makefile.ressources

module4/ressources/Makefile

-all: resources_refs.md resources_environment.md resources_refs_fr.md resources_environment_fr.md # exo1.html exo2.html exo3.html
+ressources-md: resources_refs.md resources_environment.md resources_refs_fr.md resources_environment_fr.md # exo1.html exo2.html exo3.html
 
 include ../../Makefile.ressources