remove extra colon

README.md

@@ -7779,7 +7779,7 @@ Imagine that you have a function that returns `Cow<'static, str>`. If you tell t
 
 And if you give it a `format!("{}", "My message").into()` then it will look at the type. This time it is a `String`, because `format!` makes a `String`. So this time it will select "Owned".
 
-Here is an example to test `Cow`. We will put a number into a function that returns a `Cow<'static, str>`. Depending on the number, it will create a `&str` or a `String`. Then it uses `.into()` to turn it into a `Cow`. When you do that, it will choose either `Cow:::Borrowed` or `Cow::Owned`. Then we will match to see which one it chose.
+Here is an example to test `Cow`. We will put a number into a function that returns a `Cow<'static, str>`. Depending on the number, it will create a `&str` or a `String`. Then it uses `.into()` to turn it into a `Cow`. When you do that, it will choose either `Cow::Borrowed` or `Cow::Owned`. Then we will match to see which one it chose.
 
 ```rust
 use std::borrow::Cow;