docs: fix the reference to gateway (#5546)

Author: nan-wang

docs/cloud-nativeness/k8s.md

@@ -117,7 +117,7 @@ If you want to learn more about this limitation, see [this](https://kubernetes.i
 ````
 
 ## Scaling the Gateway
-The {ref}`Gateway <flow>` is responsible for providing the API of the {ref}`Flow <flow>`.
+The {ref}`Gateway <gateway>` is responsible for providing the API of the {ref}`Flow <flow>`.
 If you have a large Flow with many Clients and many replicated Executors, the Gateway can become the bottleneck.
 In this case you can also scale up the Gateway deployment to be backed by multiple Kubernetes Pods.
 This is done by the regular means of Kubernetes: Either increase the number of replicas in the  {ref}`generated yaml configuration files <kubernetes-export>` or [add replicas while running](https://kubernetes.io/docs/concepts/workloads/controllers/deployment/#scaling-a-deployment).

docs/concepts/client/third-party-clients.md

@@ -312,5 +312,5 @@ The Flow defaults to `json` if you don't specify a sub-protocol while establishi
 ## See also
 
 - {ref}`Access a Flow with the Client <client>`
-- {ref}`Configure a Flow <flow>`
+- {ref}`Configure a Flow <flow-cookbook>`
 - [Flow REST API reference](https://api.jina.ai/rest/)

docs/concepts/flow/basics.md

@@ -32,7 +32,7 @@ jtype: Flow
 `````
 
 ```{tip}
-An empty Flow contains only {ref}`the Gateway<flow>`.
+An empty Flow contains only {ref}`the Gateway<gateway>`.
 ```
 
 ```{figure} zero-flow.svg

docs/concepts/flow/index.md

@@ -6,7 +6,7 @@ Documents "flow" through the pipeline and are processed by Executors.
 
 You can think of Flow as an interface to configure and launch your {ref}`microservice architecture <architecture-overview>`,
 while the heavy lifting is done by the {ref}`services <executor-cookbook>` themselves.
-In particular, each Flow also launches a *Gateway* service, which can expose all other services through an API that you define.
+In particular, each Flow also launches a {ref}`Gateway <gateway>` service, which can expose all other services through an API that you define.
 
 The most important methods of the `Flow` object are the following:
 

docs/concepts/gateway/index.md

@@ -1,4 +1,4 @@
-(flow)=
+(gateway)=
 
 # {fas}`door-open` Gateway