add coalesce banner to docs site (#4189)

Updates banner to point to coalesce.

background color can be changed to 047377 if purple isn't preferred

website/docusaurus.config.js

@@ -71,13 +71,13 @@ var siteSettings = {
     announcementBar: {
       id: "biweekly-demos",
       content:
-        "Join our weekly demos and see dbt Cloud in action!",
-      backgroundColor: "#047377",
+        "Register now for Coalesce 2023. The Analytics Engineering Conference!",
+      backgroundColor: "#7444FD",
       textColor: "#fff",
       isCloseable: true,
     },
     announcementBarActive: true,
-    announcementBarLink: "https://www.getdbt.com/resources/dbt-cloud-demos-with-experts/?utm_medium=event&utm_source=docs&utm_campaign=q1-2024_cloud-demos-with-experts_awareness",
+    announcementBarLink: "https://coalesce.getdbt.com/",
     // Set community spotlight member on homepage
     // This is the ID for a specific file under docs/community/spotlight
     communitySpotlightMember: "faith-lierheimer",