Add wasm plugin contribution introduction (#47)

plugins/wasm-go/README_EN.md

@@ -0,0 +1,103 @@
+## Intro
+
+This SDK is used to develop the WASM Plugins of Higress.
+## Requirements
+
+(need support Go's type parameters)
+
+Go version: >= 1.18
+
+TinyGo version: >= 0.25.0
+
+## Quick Examples
+
+Use the [request-block](example/request-block) as an example
+
+### step1. compile to wasm
+
+```bash
+tinygo build -o main.wasm -scheduler=none -target=wasi ./example/request-block/main.go
+```
+
+### step2. build&push docker image
+
+Use this [dockerfile](./Dockerfile).
+
+```bash
+docker build -t <your_registry_hub>/request-block:1.0.0 .
+docker push <your_registry_hub>/request-block:1.0.0
+```
+
+### step3. create WasmPlugin resource
+
+Read this [document](https://istio.io/latest/docs/reference/config/proxy_extensions/wasm-plugin/) to learn more about wasmplugin.
+
+```yaml
+apiVersion: extensions.istio.io/v1alpha1
+kind: WasmPlugin
+metadata:
+  name: request-block
+  namespace: higress-system
+spec:
+  selector:
+    matchLabels:
+      higress: higress-system-higress-gateway
+  pluginConfig:
+    block_urls:
+    - "swagger.html"
+  url: oci://<your_registry_hub>/request-block:1.0.0
+```
+
+If the url in request contains the `swagger.html`, the request will be blocked.
+
+```bash
+curl <your_gateway_address>/api/user/swagger.html
+```
+
+```text
+HTTP/1.1 403 Forbidden
+date: Wed, 09 Nov 2022 12:12:32 GMT
+server: istio-envoy
+content-length: 0
+```
+
+## route-level & domain-level takes effect
+
+```yaml
+apiVersion: extensions.istio.io/v1alpha1
+kind: WasmPlugin
+metadata:
+  name: request-block
+  namespace: higress-system
+spec:
+  selector:
+    matchLabels:
+      higress: higress-system-higress-gateway 
+  pluginConfig:
+   # this config will take effect globally (all incoming requests not matched by rules below)
+   block_urls:
+   - "swagger.html"
+   _rules_:
+   # route-level takes effect
+   - _match_route_:
+     - default/foo
+     # the ingress foo in namespace default will use this config
+     block_bodys:
+     - "foo"
+   - _match_route_:
+     - default/bar
+     # the ingress bar in namespace default will use this config
+     block_bodys:
+     - "bar"
+   # domain-level takes effect
+   - _match_domain_:
+     - "*.example.com"
+     # if the request's domain matched, this config will be used
+     block_bodys:
+     - "foo"
+     - "bar"
+  url: oci://<your_registry_hub>/request-block:1.0.0
+```
+
+The rules will be matched in the order of configuration. If one match is found, it will stop, and the matching configuration will take effect.
+