Backport of Add note about service upstream env var dot broken into release/1.16.x (#19398)

backport of commit 8a0896d379abf684e82a8a1f436a5758402e94f6

Co-authored-by: Tu Nguyen <im2nguyen@gmail.com>

website/content/docs/k8s/annotations-and-labels.mdx

@@ -81,6 +81,12 @@ The following Kubernetes resource annotations could be used on a pod to control
   local port to listen for those connections. When transparent proxy is enabled,
   this annotation is optional. This annotation can be either _labeled_ or _unlabeled_. We recommend the labeled format because it has a more consistent syntax and can be used to reference cluster peers as upstreams.
 
+    <Note>
+
+    If the upstream annotation contains a dot (for example, `static-server.svc:8080`), you may not be able to reference the auto-generated environment variables (`<NAME>_CONNECT_SERVICE_HOST` and `<NAME>_CONNECT_SERVICE_PORT`) since the environment variables will also contain the dot.
+
+    </Note>
+
     - **Labeled**:
 
       The labeled annotation format allows you to reference any service as an upstream. You can specify a Consul Enterprise namespace. You can also specify an admin partition in the same datacenter, a cluster peer, or a WAN-federated datacenter.

website/content/docs/k8s/connect/index.mdx

@@ -168,6 +168,12 @@ upstream. This is analogous to the standard Kubernetes service environment varia
 point instead to the correct local proxy port to establish connections via
 service mesh.
 
+<Note>
+
+If the upstream annotation contains a dot (for example, `static-server.svc:8080`), you may not be able to reference the auto-generated environment variables (`<NAME>_CONNECT_SERVICE_HOST` and `<NAME>_CONNECT_SERVICE_PORT`) since the environment variables will also contain the dot.
+
+</Note>
+
 You can verify access to the static text server using `kubectl exec`.
 Because transparent proxy is enabled by default,
 use Kubernetes DNS to connect to your desired upstream.