📖 fix typo in curl command (#3156)

fix typo in curl command

docs/book/src/quick-start.md

@@ -31,7 +31,7 @@ Install [kubebuilder](https://sigs.k8s.io/kubebuilder):
 
 ```bash
 # download kubebuilder and install locally.
-curl -L -o kubebuilder https://go.kubebuilder.io/dl/latest/$\(go env GOOS\)/$\(go env GOARCH\)
+curl -L -o kubebuilder https://go.kubebuilder.io/dl/latest/$(go env GOOS)/$(go env GOARCH)
 chmod +x kubebuilder && mv kubebuilder /usr/local/bin/
 ```
 
@@ -262,4 +262,4 @@ complexities of achieving this goal while allowing users to customize the genera
 [go-modules-blogpost]: https://blog.golang.org/using-go-modules
 [envtest]: https://book.kubebuilder.io/reference/testing/envtest.html
 [architecture-concept-diagram]: architecture.md
-[kustomize]: https://github.com/kubernetes-sigs/kustomize
+[kustomize]: https://github.com/kubernetes-sigs/kustomize