Remove duplicate :disabled (#2195)

`:disabled` is listed twice in this table.

Author: tylerwoodcook

css.md

@@ -59,7 +59,6 @@ keywords:
 | -------------------- | ------------------------------------------ |
 | `:target`            | eg, `h2#foo:target`                        |
 | ---                  | ---                                        |
-| `:disabled`          |                                            |
 | `:focus`             |                                            |
 | `:active`            |                                            |
 | ---                  | ---                                        |