Improve documentation for usage of Kubernetes Ingress

docs/content/middlewares/overview.md

@@ -25,7 +25,7 @@ whoami:
     - "traefik.http.routers.router1.middlewares=foo-add-prefix@docker"
 ```
 
-```yaml tab="Kubernetes"
+```yaml tab="Kubernetes IngressRoute"
 # As a Kubernetes Traefik IngressRoute
 apiVersion: apiextensions.k8s.io/v1beta1
 kind: CustomResourceDefinition
@@ -148,6 +148,9 @@ then you'll have to append to the middleware name, the `@` separator, followed b
     In this case, since the definition of the middleware is not in kubernetes,
     specifying a "kubernetes namespace" when referring to the resource does not make any sense,
     and therefore this specification would be ignored even if present.
+    On the other hand, if you declare the middleware as a Custom Resource in Kubernetes and use the 
+    non-crd Ingress objects, you'll have to add the kubernetes namespace of the middleware to the 
+    annotation like this `<middleware-namespace>-<middleware-name>@kubernetescrd`.
 
 !!! abstract "Referencing a Middleware from Another Provider"
 
@@ -178,7 +181,7 @@ then you'll have to append to the middleware name, the `@` separator, followed b
         - "traefik.http.routers.my-container.middlewares=add-foo-prefix@file"
     ```
 
-    ```yaml tab="Kubernetes"
+    ```yaml tab="Kubernetes Ingress Route"
     apiVersion: traefik.containo.us/v1alpha1
     kind: IngressRoute
     metadata:
@@ -199,6 +202,31 @@ then you'll have to append to the middleware name, the `@` separator, followed b
             # A namespace specification such as above is ignored
             # when the cross-provider syntax is used.
     ```
+    
+    ```yaml tab="Kubernetes Ingress"
+    apiVersion: traefik.containo.us/v1alpha1
+    kind: Middleware
+    metadata:
+      name: stripprefix
+      namespace: appspace
+    spec:
+      stripPrefix:
+        prefixes:
+          - /stripit
+    
+    ---
+    apiVersion: networking.k8s.io/v1
+    kind: Ingress
+    metadata:
+      name: ingress
+      namespace: appspace
+      annotations:
+        # referencing a middleware from Kubernetes CRD provider: 
+        # <middleware-namespace>-<middleware-name>@kubernetescrd
+        "traefik.ingress.kubernetes.io/router.middlewares": appspace-stripprefix@kubernetescrd
+    spec:
+      # ... regular ingress definition
+    ```
 
 ## Available Middlewares