fix: 更改 book 为 books，确保准确性

app/src/main/res/layout/activity_remote_book.xml

@@ -30,6 +30,15 @@
             android:layout_width="match_parent"
             android:layout_height="match_parent" />
 
+        <io.legado.app.ui.widget.anima.RotateLoading
+            android:id="@+id/rotate_loading"
+            android:layout_width="36dp"
+            android:layout_height="36dp"
+            android:layout_margin="6dp"
+            android:visibility="gone"
+            android:layout_gravity="center"
+            app:loading_width="2dp" />
+
     </io.legado.app.ui.widget.dynamiclayout.DynamicFrameLayout>
 
     <!--    <io.legado.app.ui.widget.SelectActionBar-->
@@ -47,10 +56,12 @@
         android:layout_margin="16dp"
         android:gravity="center"
         android:visibility="gone"
-        android:text="webDav book文件夹为空"
+        android:text="webDav books文件夹为空"
         app:layout_constraintTop_toBottomOf="@+id/title_bar"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintLeft_toLeftOf="parent"
         app:layout_constraintRight_toRightOf="parent"
         tools:text="Empty" />
+
+
 </androidx.constraintlayout.widget.ConstraintLayout>