message: docs: fix example of a WASM filter
diff: @@ -36,13 +36,12 @@ class ExampleContext : public Context {
  public:
  explicit ExampleContext(uint32_t id, RootContext* root) : Context(id, root) {}
  - FilterHeadersStatus onRequestHeaders() override;
  - FilterDataStatus onRequestBody(size_t body_buffer_length, bool end_of_stream) override;
  + FilterHeadersStatus onRequestHeaders(uint32_t headers) override;
  void onDone() override;
  };
  static RegisterContextFactory register_ExampleContext(CONTEXT_FACTORY(ExampleContext));
  -FilterHeadersStatus ExampleContext::onRequestHeaders() {
  +FilterHeadersStatus ExampleContext::onRequestHeaders(uint32_t headers) {
  logInfo(std::string("onRequestHeaders ") + std::to_string(id()));
  auto path = getRequestHeader(":path");
  logInfo(std::string("header path ") + std::string(path->view()));
  