Add all social icons in navbar

Author: shravanngoswamii

_quarto.yml

@@ -32,6 +32,12 @@ website:
       - icon: twitter
         text: Turing Twitter
         href: https://x.com/TuringLang
+      - icon: chat-dots
+        text: Turing Discourse
+        href: https://discourse.julialang.org/c/domain/probprog/48
+      - icon: slack
+        text: Turing Slack
+        href: https://julialang.slack.com/archives/CCYDC34A0
       - icon: github
         text: Turing GitHub
         href: https://github.com/TuringLang