Fix typo

Author: odersky

docs/docs/reference/overview.md

@@ -74,7 +74,7 @@ Listed in this section are new language constructs that help precise, typechecke
    ([Pending](https://github.com/lampepfl/dotty/pull/4229))
    Implicit conversions are very easily mis-used, which makes them the cause of much suprising behavior.
    We now require a language feature import not only when an implicit conversion is defined
-   by also when it is applied. This protects users of libraries that define implicit conversions
+   but also when it is applied. This protects users of libraries that define implicit conversions
    from being bitten by unanticipated feature interactions.
 
  - Null safety