Added hint about manual synchronization

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

@@ -40,6 +40,19 @@
                 app:layout_constraintStart_toStartOf="parent"
                 app:layout_constraintTop_toBottomOf="@id/swEnabled" />
 
+            <TextView
+                android:id="@+id/tvManalHint"
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="6dp"
+                android:layout_marginEnd="48dp"
+                android:text="@string/title_advanced_manual_hint"
+                android:textAppearance="@style/TextAppearance.AppCompat.Small"
+                android:textStyle="italic"
+                app:layout_constraintEnd_toEndOf="parent"
+                app:layout_constraintStart_toStartOf="parent"
+                app:layout_constraintTop_toBottomOf="@id/tvEnabledHint" />
+
             <TextView
                 android:id="@+id/tvWhen"
                 android:layout_width="0dp"
@@ -51,7 +64,7 @@
                 android:textColor="?android:attr/textColorPrimary"
                 app:layout_constraintEnd_toEndOf="parent"
                 app:layout_constraintStart_toStartOf="parent"
-                app:layout_constraintTop_toBottomOf="@id/tvEnabledHint" />
+                app:layout_constraintTop_toBottomOf="@id/tvManalHint" />
 
             <Spinner
                 android:id="@+id/spPollInterval"

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

@@ -232,6 +232,7 @@
     <string name="title_advanced_last_cleanup">Last cleanup: %1$s</string>
 
     <string name="title_advanced_enabled_hint">Globally disable or enable receiving of messages</string>
+    <string name="title_advanced_manual_hint">If synchronization is disabled, it is still possible to synchronize manually by pulling down the message list. This will synchronize messages and execute operations for a limited time.</string>
     <string name="title_advanced_schedule_hint">Tap on a time to set a time</string>
     <string name="title_advanced_metered_hint">Metered connections are generally mobile connections or paid Wi-Fi hotspots</string>
     <string name="title_advanced_metered_warning">Disabling this option will disable receiving and sending messages on mobile internet connections</string>