Add mod documentation in seven languages

locale/ui_en.properties

@@ -1,5 +1,5 @@
-mod_items_editor_name = Item Editor
-mod_items_editor_desc = Editor of the game's items: a searchable list with pictures, name and description in every language of the mod, price, icon, types and the use action; a save shows in the game at once.
+mod_items_editor_name = Items Editor
+mod_items_editor_desc = Edits a mod's items while the game runs: names and descriptions in every language, price, picture, types and the use action. The game shows a save at once.
 tools/items_editor/title = Items
 tools/items_editor/name = Name
 tools/items_editor/description = Description