fix up crate/trait discrepancy, clarify language

src/librustc_resolve/diagnostics.rs

@@ -106,8 +106,8 @@ mod foo {
 use foo::MyTrait::doSomething;
 ```
 
-In general, it's not legal to directly import functions from a crate or
+In general, it's not legal to directly import methods belonging to a
-concrete type.
+trait or concrete type.
 "##,
 
 E0255: r##"