Add extended tooltips

mods/ITEMS/mcl_books/init.lua

@@ -110,6 +110,7 @@ end
 -- Book and Quill
 minetest.register_craftitem("mcl_books:writable_book", {
 	description = S("Book and Quill"),
+	_tt_help = S("Write down some notes"),
 	_doc_items_longdesc = S("This item can be used to write down some notes."),
 	_doc_items_usagehelp = S("Hold it in the hand, then rightclick to read the current notes and edit then. You can edit the text as often as you like. You can also sign the book which turns it into a written book which you can stack, but it can't be edited anymore.").."\n"..
 	S("A book can hold up to 4500 characters. The title length is limited to 64 characters."),