Add link to WebRTC guide in libp2p docs (#692)

* add WebRTC guide

* add header image

* Optimised images with calibre/image-actions

* update image

* fix date

---------

Co-authored-by: Daniel N <2color@users.noreply.github.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

src/_blog/tutorials.md

@@ -4,6 +4,16 @@ type: Tutorial
 sitemap:
   exclude: true
 data:
+- title: Browser P2P Connectivity With WebRTC and js-libp2p
+  date: 2024-06-12
+  publish_date: 
+  path: https://docs.libp2p.io/guides/getting-started/webrtc/
+  card_image: "/libp2p-webrtc.png"
+  tags:
+  - libp2p
+  - WebRTC
+  - tutorial
+  - pubsub
 - title: Uploading Files to IPFS from a Web Application
   date: 2021-06-28
   publish_date: