Document F5 keyboard shortcut in editor (#3061)

Show what the F5 key does in the editor, when someone opens the Keyboard
Shortcuts menu while paused.

F5 keyboard shortcut toggles autotiling in the editor.

src/supertux/menu/editor_menu.cpp

@@ -202,7 +202,7 @@ EditorMenu::menu_action(MenuItem& item)
 	case MNID_HELP:
     {
       auto dialog = std::make_unique<Dialog>();
-      dialog->set_text(_("Keyboard Shortcuts:\n---------------------\nEsc = Open Menu\nCtrl+S = Save\nCtrl+T = Test\nCtrl+Z = Undo\nCtrl+Y = Redo\nF6 = Render Light\nF7 = Grid Snapping\nF8 = Show Grid\nCtrl++ or Ctrl+Scroll Up = Zoom In\nCtrl+- or Ctrl+Scroll Down = Zoom Out\nCtrl+D = Reset Zoom\n\nScripting Shortcuts:\n    -------------    \nHome = Go to beginning of line\nEnd = Go to end of line\nLeft arrow = Go back in text\nRight arrow = Go forward in text\nBackspace = Delete in front of text cursor\nDelete = Delete behind text cursor\nCtrl+X = Cut whole line\nCtrl+C = Copy whole line\nCtrl+V = Paste\nCtrl+D = Duplicate line\nCtrl+Z = Undo\nCtrl+Y = Redo"));
+      dialog->set_text(_("Keyboard Shortcuts:\n---------------------\nEsc = Open Menu\nCtrl+S = Save\nCtrl+T = Test\nCtrl+Z = Undo\nCtrl+Y = Redo\nF5 = Toggle Autotiling\nF6 = Render Light\nF7 = Grid Snapping\nF8 = Show Grid\nCtrl++ or Ctrl+Scroll Up = Zoom In\nCtrl+- or Ctrl+Scroll Down = Zoom Out\nCtrl+D = Reset Zoom\n\nScripting Shortcuts:\n    -------------    \nHome = Go to beginning of line\nEnd = Go to end of line\nLeft arrow = Go back in text\nRight arrow = Go forward in text\nBackspace = Delete in front of text cursor\nDelete = Delete behind text cursor\nCtrl+X = Cut whole line\nCtrl+C = Copy whole line\nCtrl+V = Paste\nCtrl+D = Duplicate line\nCtrl+Z = Undo\nCtrl+Y = Redo"));
       dialog->add_cancel_button(_("Got it!"));
       MenuManager::instance().set_dialog(std::move(dialog));
     }