fix example

SPEC.md

@@ -359,7 +359,7 @@ WDL also provides features for implementing more complex workflows. For example,
   ```json
   {
     "hello_parallel.pattern": "^[a-z_]+$",
-    "hello_parallel.files": ["/greetings.txt", "greetings2.txt"]
+    "hello_parallel.files": ["greetings.txt", "hello.txt"]
   }
   ```