fix pre block indentation/spaces

todo.md

@@ -2,20 +2,8 @@
 
 - add message in status bar 
 - add **custom css** feature @done
-- sync scroll @done @improve: scroll preview to center when possible
+- sync scroll @done
 - regive focus to the right markdown view @done
 - set the title of the preview @done
 - disable previewing when the preview is closed @done
 - check when setting is activated and create panel and stuff @done
-
-This is pretty cool
-
-```ruby
-print('hello world')
-def test():
-    puts 'hello'
-    if test:
-        print('hi')
-```
-
-this is some `code`!