Rephrased File manager description

From file resources to file manager. Clarified wording to say it allows download and upload of documents (instead of files, so people do not get confused with zim-manager).

src/offspot_config/catalog.json

@@ -152,8 +152,8 @@
         "ident": "file-manager.offspot.kiwix.org",
         "domain": "resources",
         "kind": "app",
-        "title": "File Resources",
-        "description": "View and download resources",
+        "title": "File Manager",
+        "description": "Upload and download documents",
         "languages": [
             "mul"
         ],