POP3: added remark about maximum number of messages

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

@@ -500,6 +500,18 @@
             app:layout_constraintStart_toStartOf="parent"
             app:layout_constraintTop_toBottomOf="@id/cbLeaveDevice" />
 
+        <TextView
+            android:id="@+id/tvMaxKeep"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="6dp"
+            android:labelFor="@+id/etMax"
+            android:text="@string/title_max_messages_keep"
+            android:textAppearance="@style/TextAppearance.AppCompat.Small"
+            android:textStyle="italic"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/tvMax" />
+
         <eu.faircode.email.EditTextPlain
             android:id="@+id/etMax"
             android:layout_width="match_parent"
@@ -508,7 +520,7 @@
             android:maxLength="9"
             android:textAppearance="@style/TextAppearance.AppCompat.Medium"
             app:layout_constraintStart_toStartOf="parent"
-            app:layout_constraintTop_toBottomOf="@id/tvMax" />
+            app:layout_constraintTop_toBottomOf="@id/tvMaxKeep" />
 
         <TextView
             android:id="@+id/tvMaxRemark"

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

@@ -1140,6 +1140,7 @@
     <string name="title_leave_deleted">Leave deleted messages on server</string>
     <string name="title_leave_on_device">Leave messages on device</string>
     <string name="title_max_messages">Maximum number of messages to download (blank for all)</string>
+    <string name="title_max_messages_keep">This is the maximum number of messages that will be kept on the device</string>
     <string name="title_max_messages_remark">
         Enter a positive number to download the messages at the end (most common)
         and a negative number to download the messages at the beginning (least common)