WebContent: Pledge "recvfd" :^)

This is needed so we can receive file descriptors from ProtocolServer.

Fixes SerenityOS#4660.

Services/WebContent/main.cpp

@@ -32,7 +32,7 @@
 int main(int, char**)
 {
  Core::EventLoop event_loop;
- if (pledge("stdio shared_buffer accept unix rpath", nullptr) < 0) {
+ if (pledge("stdio shared_buffer accept unix rpath recvfd", nullptr) < 0) {
  perror("pledge");
  return 1;
  }