README: clarify relative complement (#674)

README.md

@@ -207,7 +207,7 @@ combiner even if `or` is used (this is an API implementation specificity).
 | ------------------- | :----------: | ------- |
 |`or`/`,` combiner <br> (union) | ![Union of queries](img/union.svg)  | `> .5% or last 2 versions` <br> `> .5%, last 2 versions` |
 | `and` combiner <br> (intersection) | ![intersection of queries](img/intersection.svg) | `> .5% and last 2 versions` |
-| `not` combiner <br> (relative complement) | ![Relative complement of queries](img/complement.svg) | All those three are equivalent to the first one <br> `> .5% and not last 2 versions` <br> `> .5% or not last 2 versions` <br> `> .5%, not last 2 versions` |
+| `not` combiner <br> (relative complement) | ![Relative complement of queries](img/complement.svg) | These three are equivalent to one another: <br> `> .5% and not last 2 versions` <br> `> .5% or not last 2 versions` <br> `> .5%, not last 2 versions` |
 
 _A quick way to test your query is to do `npx browserslist '> 0.5%, not IE 11'`
 in your terminal._