Update BAD Example in import-alias.md

This update refines the BAD example in import-alias.md to better illustrate improper usage of import aliases, making it easier for readers to understand and learn from the mistake.

src/import-alias.md

@@ -25,7 +25,7 @@ import (
   "fmt"
   "os"
 
-
+  runtimetrace "runtime/trace"
   nettrace "golang.net/x/trace"
 )
 ```