fix ack-generate: command not found

Author: Kumar Gaurav Sharma

scripts/build-controller.sh

@@ -53,7 +53,7 @@ Environment variables:
                             instruct the code generator for the service.
                             Default: services/{SERVICE}/generator.yaml
   AWS_SDK_GO_VERSION:       Overrides the version of github.com/aws/aws-sdk-go used
-                            by `ack-generate` to fetch the service API Specifications.
+                            by 'ack-generate' to fetch the service API Specifications.
   TEMPLATES_DIR:            Overrides the directory containg ack-generate templates
                             Default: $TEMPLATES_DIR
   K8S_RBAC_ROLE_NAME:       Name of the Kubernetes Role to use when generating