Fix a minor typo in the help text for a feature flag task.

service/src/main/java/org/whispersystems/textsecuregcm/workers/SetFeatureFlagTask.java

@@ -34,7 +34,7 @@ public class SetFeatureFlagTask extends AbstractFeatureFlagTask {
             out.println();
             printFeatureFlags(out);
         } else {
-            out.println("Usage: set-feature-flag?flag=FLAG_NAME&value=[true|false]");
+            out.println("Usage: set-feature-flag?flag=FLAG_NAME&active=[true|false]");
         }
     }
 }