Move csvxml translations to a separate git submodule and add help texts

Close #22

.gitmodules

@@ -16,9 +16,9 @@
 [submodule "l10n/musdb"]
 	path = l10n/musdb
 	url = gitea:museum-digital/translation-musdb.git
-[submodule "l10n/importer"]
-	path = l10n/importer
-	url = gitea:museum-digital/translations-importer.git
 [submodule "classes/MD_QA"]
 	path = classes/MD_QA
 	url = gitea:museum-digital/MD_QA.git
+[submodule "l10n/translation-csvxml"]
+	path = l10n/translation-csvxml
+	url = gitea:museum-digital/translation-csvxml.git