add px-peer config for example

examples/lightpush_publisher_mix.nim

@@ -90,6 +90,14 @@ proc setupAndPublish(rng: ref HmacDrbgContext, conf: LPMixConf) {.async.} =
     @[MultiAddress.init(conf.destPeerAddr).get()],
   )
   node.peerManager.addServicePeer(pxPeerInfo, WakuPeerExchangeCodec)
+
+
+  let pxPeerInfo1 = RemotePeerInfo.init(
+    conf.pxId,
+    @[MultiAddress.init(conf.pxAddr).get()],
+  )
+  node.peerManager.addServicePeer(pxPeerInfo1, WakuPeerExchangeCodec)
+
   let keyPairResult = generateKeyPair()
   if keyPairResult.isErr:
     return

examples/lightpush_publisher_mix_config.nim

@@ -15,6 +15,17 @@ type
         name: "dp-id",
     }: string
 
+    pxAddr* {.
+        desc: "Peer exchange address.",
+        defaultValue: "localhost:50001",
+        name: "px-addr",
+    }: string
+    pxId* {.
+        desc: "Peer exchange ID.",
+        defaultValue: "waku-v2-peer-exchange",
+        name: "px-id",
+    }: string
+
     port* {.
         desc: "Port to listen on.",
         defaultValue: 50000,