Add clean summary

mobile/src/main/res/values-zh-rCN/strings.xml

@@ -70,6 +70,7 @@
     <string name="settings_service_upstream">上游网络接口</string>
     <string name="settings_service_upstream_auto">自动检测系统 VPN</string>
     <string name="settings_service_clean">清理/重新应用路由规则</string>
+    <string name="settings_service_clean_summary">将修改的设置应用到当前启用的服务上。也可用于修复偶尔会发生的竞态条件。</string>
     <string name="settings_misc">杂项</string>
     <string name="settings_misc_logcat">导出调试信息</string>
     <string name="settings_misc_logcat_summary">这种非常有用哇</string>

mobile/src/main/res/values/strings.xml

@@ -75,6 +75,8 @@
     <string name="settings_service_upstream">Upstream network interface</string>
     <string name="settings_service_upstream_auto">Auto detect system VPN</string>
     <string name="settings_service_clean">Clean/reapply routing rules</string>
+    <string name="settings_service_clean_summary">Update changed settings to current active services. Can also fix rare
+        race conditions.</string>
     <string name="settings_misc">Misc</string>
     <string name="settings_misc_logcat">Export debug information</string>
     <string name="settings_misc_logcat_summary">Such useful very wow</string>

mobile/src/main/res/xml/pref_settings.xml

@@ -5,7 +5,8 @@
         <Preference
             android:key="service.clean"
             android:icon="@drawable/ic_action_settings_backup_restore"
-            android:title="@string/settings_service_clean"/>
+            android:title="@string/settings_service_clean"
+            android:summary="@string/settings_service_clean_summary"/>
         <SwitchPreference
             android:key="service.masquerade"
             android:icon="@drawable/ic_social_people"