Update article.md

"but strongly" -> "but is strongly". "is strongly not recommended" is still a bit odd, though it's readable and totally understandable. Could maybe be changed to "but is strongly discouraged". Still, not bad as (now) is.

Author: paroche

2-ui/2-events/01-introduction-browser-events/article.md

@@ -181,7 +181,7 @@ button.onclick = function() {
 
 **Use functions, not strings.**
 
-The assignment `elem.onclick = "alert(1)"` would work too. It works for compatibility reasons, but strongly not recommended.
+The assignment `elem.onclick = "alert(1)"` would work too. It works for compatibility reasons, but is strongly not recommended.
 
 **Don't use `setAttribute` for handlers.**