Revert "Redesigned top nav and footer (#5113)" (#5560)

This reverts commit dadb6b1.

_data/alert.yml

@@ -1 +1 @@
-message: false
+message: "[OpenSearch 2.3 is live 🍾!](/downloads.html)"

_data/top_nav.yml

@@ -1,33 +1,26 @@
 items:
   -
     label: OpenSearchCon
-    fragments: 
-      - opensearchcon
-      - sessions
-      - speakers
-      - exhibitors
-      - workshops
-      - unconference
-      - opensearchcon2023-cfp
+    fragment: opensearchcon
     children:
       -
-        label: 2024 - Stay Informed
-        url: /events/opensearchcon/
+        label: Register for OpenSearchCon!
+        url: https://opensearchcon2023.splashthat.com
       -
         label: Sessions
-        url: /events/opensearchcon/sessions/
+        url: /events/opensearchcon/sessions/index.html
       -
         label: Speakers
-        url: /events/opensearchcon/speakers/
+        url: /events/opensearchcon/speakers/index.html
       -
         label: Exhibitors
-        url: /events/opensearchcon/exhibitors/
+        url: /events/opensearchcon/exhibitors/index.html
       -
         label: Workshops
-        url: /events/opensearchcon/workshops/
+        url: /events/opensearchcon/workshops/index.html
       -
         label: Unconference
-        url: /events/opensearchcon/unconference/
+        url: /events/opensearchcon/unconference/index.html
       -
         label: CFP is closed
         url: /opensearchcon2023-cfp.html
@@ -39,19 +32,17 @@ items:
     url: /downloads.html
   -
     label: About
-    url: /about.html
     fragments:
       - about
       - releases
-      - roadmap
       - faq
     children:
+      -
+       label: OpenSearch
+       url: /about.html
       -
        label: Releases
        url: /releases.html
-      -
-       label: Roadmap
-       url: https://github.com/orgs/opensearch-project/projects/1
       -
        label: FAQ
        url: /faq
@@ -88,22 +79,8 @@ items:
     url: /docs/
   -
     label: Platform
-    url: /platform/index.html
-    fragments: 
-      - platform
-      - search
-      - observability
-      - security-analytics
-      - vector-database
-      - benchmarks
+    fragment: platform
     children:
-      - label: Search
-        url: /platform/search/index.html
-      - label: Observability
-        url: /platform/observability/index.html
-      -
-        label: Security Analytics
-        url: /platform/security-analytics/index.html
       -
         label: Vector Database
         url: /platform/search/vector-database.html
@@ -113,3 +90,4 @@ items:
       -
         label: Performance Benchmarks
         url: /benchmarks
+