Clean up E0283 explanation

src/librustc_error_codes/error_codes/E0283.md

@@ -1,7 +1,6 @@
-This error occurs when the compiler doesn't have enough information
-to unambiguously choose an implementation.
+An implementation cannot be chosen unambiguously because of lack of information.
 
-For example:
+Erroneous code example:
 
 ```compile_fail,E0283
 trait Generator {
@@ -27,7 +26,9 @@ fn main() {
 }
 ```
 
-To resolve this error use the concrete type:
+This error can be solved by adding type annotations that provide the missing
+information to the compiler. In this case, the solution is to use a concrete
+type:
 
 ```
 trait Generator {