[docs] Add transactions in the sidebar (apache#8692)

* add transaction in the sidebar

* keep transactions consitent in the docs

* update

* update

site2/docs/concepts-transactions.md

@@ -1,7 +1,7 @@
 ---
-id: transaction
+id: transactions
 title: Transactions
-sidebar_label: Transaction Concepts
+sidebar_label: Overview
 ---
 
 Transactional semantics enable event streaming applications to consume, process, and produce messages in one atomic operation. In Pulsar, a producer or consumer can work with messages across multiple topics and partitions and ensure those messages are processed as a single unit. 

site2/docs/transaction-api.md

@@ -1,7 +1,7 @@
 ---
-id: transaction-api
-title: Transaction API(Developer Preview)
-sidebar_label: Transaction API
+id: transactions-api
+title: Transactions API (Developer Preview)
+sidebar_label: Transactions API
 ---
 
 All messages in a transaction is available only to consumers after the transaction is committed. If a transaction is aborted, all the writes and acknowledgments in this transaction rollback. 

site2/docs/transaction-guarantee.md

@@ -1,7 +1,7 @@
 ---
-id: transaction-guarantee
-title: Transaction Guarantee
-sidebar_label: Transaction Guarantee
+id: transactions-guarantee
+title: Transactions Guarantee
+sidebar_label: Transactions Guarantee
 ---
 
 Pulsar transactions support the following guarantee.

site2/website/sidebars.json

@@ -1,11 +1,9 @@
 {
   "docs": {
     "Get started": [
-      "pulsar-2.0",
       "standalone",
       "standalone-docker",
-      "kubernetes-helm",
-      "client-libraries"
+      "kubernetes-helm"
     ],
     "Concepts and Architecture": [
       "concepts-overview",
@@ -56,6 +54,11 @@
      "tiered-storage-aws",
      "tiered-storage-gcs",
      "tiered-storage-filesystem"
+  ],
+  "Transactions": [
+    "transactions",
+    "transactions-guarantee",
+    "transactions-api"
   ],
     "Kubernetes (Helm)": [
       "helm-overview",