chore: add documentation build in the makefile (#1105)

Author: remyleone

docs/Makefile

@@ -17,4 +17,7 @@ help:
 # Catch-all target: route all unknown targets to Sphinx using the new
 # "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
 %: Makefile
+	sphinx-apidoc -f -o ./source ../scaleway-core
+	sphinx-apidoc -f -o ./source ../scaleway
+	sphinx-apidoc -f -o ./source ../scaleway-async
 	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)