Merge pull request #13 from roundcube/fix-output-to-en_US

Write en docs to …/en_US to serve published URL

Makefile

@@ -23,7 +23,7 @@ clean:
 	mkdir -p $(BUILDDIR)/locale/_plugins
 
 html: conf.py _static/default.css
-	$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(SOURCE) $(BUILDDIR)/html/doc/help/$(VERSION)/$(LANGUAGE)
+	$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(SOURCE) $(BUILDDIR)/html/doc/help/$(VERSION)/$(SOURCE)
 	@echo
 	@echo "Build finished. The HTML pages are in $(BUILDDIR)/html/doc/help/$(VERSION)/$(SOURCE)."