conversation: fix strings.xml description of file saving

Change-Id: I294a4bc32ef41cd50c2a7251c0df5057446d63b6
Gitlab: #584

ring-android/app/src/main/res/menu/conversation_item_actions_file.xml

@@ -16,7 +16,7 @@
     <item
         android:id="@+id/conv_action_download"
         android:icon="@drawable/ic_file_download"
-        android:title="@string/menu_file_download"
+        android:title="@string/menu_file_save"
         app:showAsAction="ifRoom" />
 
     <item

ring-android/app/src/main/res/values/strings.xml

@@ -279,7 +279,8 @@ along with this program; if not, write to the Free Software
     <string name="no_space_left_on_device">No space left on device</string>
     <string name="title_media_viewer">Media viewer</string>
     <string name="menu_file_open">Open file</string>
-    <string name="menu_file_download">Save file</string>
+    <string name="menu_file_download">Download file</string>
+    <string name="menu_file_save">Save file</string>
     <string name="menu_file_delete">Delete file</string>
     <string name="menu_file_share">Share file</string>
     <string name="menu_message_copy">Copy</string>