docs: modify scripts path (#587)

Issue #, if available: None

Description of changes: Update the outdated relative link to the build script.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Author: augustkang

cmd/ack-generate/README.md

@@ -3,7 +3,7 @@
 ## tl;dr
 
 If you want to just build a service controller, there's a
-[script](../scripts/build-controller.sh) for that:
+[script](/scripts/build-controller.sh) for that:
 
 For example, to generate the SNS service controller for ACK: