Update 3.2-backend.md

src/3.2-backend.md

@@ -9,7 +9,7 @@ There are two steps to add a query:
 ```
 rustc_queries! {
    query new_query(_: DefId) -> () {
-        desc { "check safedrop bugs in rustc mir" }
+        desc { "a new query with novel features" }
    }
 }
 ```