Update istio docs according latest istio release (#3646)

* Update istio docs according latest istio release

* Rename skywalingadapter.yml to skywalkingadapter.yml

Rename typo file name.

* Update README.md

Add a link to doc.

* Update README.md

docs/en/setup/istio/README.md

@@ -13,5 +13,12 @@ Follow the [deploying backend in kubernetes](../backend/backend-k8s.md) to insta
 
 ## Setup Istio to send metrics to oap
 
-The SkyWalking uses Istio bypass adapter collects metrics. Use `kubectl apply -f` with the `yaml`(s) in [the yaml folder](yaml) to setup.
+1. Install Istio metric template
 
+`kubectl apply -f https://raw.githubusercontent.com/istio/istio/1.3.3/mixer/template/metric/template.yaml`
+
+2. Install SkyWalking adapter
+
+`kubectl apply -f skywalkingadapter.yml`
+
+Find the `skywalkingadapter.yml` at [here](yaml/skywalkingadapter.yml).

docs/en/setup/istio/yaml/02-skywalingadapter.yml

-# Licensed to the Apache Software Foundation (ASF) under one
-# or more contributor license agreements.  See the NOTICE file
-# distributed with this work for additional information
-# regarding copyright ownership.  The ASF licenses this file
-# to you under the Apache License, Version 2.0 (the
-# "License"); you may not use this file except in compliance
-# with the License.  You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-apiVersion: "config.istio.io/v1alpha2"
-kind: adapter
-metadata:
-  name: swadapter
-  namespace: istio-system
-spec:
-  description:
-  session_based: false
-  templates:
-  - metric

docs/en/setup/istio/yaml/03-operator_cfg.yml → docs/en/setup/istio/yaml/skywalkingadapter.yml

@@ -14,6 +14,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+apiVersion: "config.istio.io/v1alpha2"
+kind: adapter
+metadata:
+  name: swadapter
+  namespace: istio-system
+spec:
+  description:
+  session_based: false
+  templates:
+  - metric
+---
+
 apiVersion: "config.istio.io/v1alpha2"
 kind: handler
 metadata: