Add IST0137 analyzer docs (#9239)

* Add ist0137 analyzer docs

* > fix description

* Update content/en/docs/reference/config/analysis/ist0137/index.md

Co-authored-by: Eric Van Norman <ericvn@us.ibm.com>

Co-authored-by: Eric Van Norman <ericvn@us.ibm.com>

content/en/docs/reference/config/analysis/ist0137/index.md

@@ -0,0 +1,47 @@
+---
+title: DeploymentConflictingPorts
+layout: analysis-message
+owner: istio/wg-user-experience-maintainers
+test: n/a
+---
+
+This message occurs when two services select the same workload with the same `targetPort` but different `port`s.
+
+## An example
+
+Consider an Istio mesh with the following services:
+
+{{< text yaml >}}
+apiVersion: v1
+kind: Service
+metadata:
+  name: nginx-a
+spec:
+  ports:
+    - port: 8080
+      protocol: TCP
+      targetPort: 80
+  selector:
+    app: nginx
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: nginx-b
+spec:
+  ports:
+    - port: 80
+      protocol: TCP
+      targetPort: 80
+  selector:
+    app: nginx
+{{< /text >}}
+
+In this example, service `nginx-a` and service `nginx-b` select the same workload `nginx` with the same `targetPort` but different `port`s.
+
+## How to resolve
+
+This may be fixed in one of two ways:
+
+- Make both services use the same `port`. This will require reconfiguring the clients of one of the services to connect to a different `port`.
+- Make both services use different `targetPort`s. This will require configuring the workload pods of one of the services to listen on the same `targetPort` as the other service.