Update E0425 error explanation

src/librustc_resolve/diagnostics.rs

@@ -632,8 +632,8 @@ fn bar() {
 let x = unknown_variable;  // error: unresolved name `unknown_variable`
 ```
 
-Please verify you didn't misspell the name or that you're not using an
-invalid object. Example:
+Please verify that the name wasn't misspelled and ensure that the
+identifier being referred to is valid for the given situation. Example:
 
 ```
 enum something_that_does_exist {