refactor: remove RSS support from social configuration

- Eliminated the RSS field from social settings in configuration files and UI schemas.
- Updated related documentation and localization files to reflect the removal of RSS support.
- Adjusted components to ensure compatibility with the updated social configuration.

Signed-off-by: Innei <tukon479@gmail.com>

config.example.json

@@ -11,8 +11,7 @@
   },
   "social": {
     "github": "",
-    "twitter": "",
-    "rss": false
+    "twitter": ""
   },
   "feed": {
     "folo": {
@@ -27,4 +26,4 @@
   ],
   "mapStyle": "builtin",
   "mapProjection": "mercator"
-}
+}