Fix typo in impl_trait.md

Author: Shark

src/trait/impl_trait.md

@@ -28,7 +28,7 @@ fn parse_csv_document<R: std::io::BufRead>(src: R) -> std::io::Result<Vec<Vec<St
 ```
 
 `parse_csv_document` is generic, allowing it to take any type which implements BufRead, such as `BufReader<File>` or `[u8]`,
-but it's not important what type `R` is, and `R` is only used to declare the type of `src`, so the function can also be written an
+but it's not important what type `R` is, and `R` is only used to declare the type of `src`, so the function can also be written as:
 
 ```rust,editable
 fn parse_csv_document(src: impl std::io::BufRead) -> std::io::Result<Vec<Vec<String>>> {
@@ -46,7 +46,7 @@ fn parse_csv_document(src: impl std::io::BufRead) -> std::io::Result<Vec<Vec<Str
 }
 ```
 
-Note that using `impl Trait` as an argument type means that you cannot explicitly state what form of the function you use, i.e. `parse_csv_document::<std::io::Empty>(std::io::empty())` will not work with the second example
+Note that using `impl Trait` as an argument type means that you cannot explicitly state what form of the function you use, i.e. `parse_csv_document::<std::io::Empty>(std::io::empty())` will not work with the second example.
 
 
 ## As a return type