Doc: Add FAQ: store additional info in Node

openraft/src/docs/faq/faq-toc.md

@@ -9,6 +9,7 @@
 - [Cluster management](#cluster-management)
   * [How to initialize a cluster?](#how-to-initialize-a-cluster)
   * [Are there any issues with running a single node service?](#are-there-any-issues-with-running-a-single-node-service)
+  * [How do I store additional information about nodes in Openraft?](#how-do-i-store-additional-information-about-nodes-in-openraft)
   * [How to remove node-2 safely from a cluster `{1, 2, 3}`?](#how-to-remove-node-2-safely-from-a-cluster-1-2-3)
   * [What actions are required when a node restarts?](#what-actions-are-required-when-a-node-restarts)
   * [What will happen when data gets lost?](#what-will-happen-when-data-gets-lost)

openraft/src/docs/faq/faq.md

@@ -98,6 +98,40 @@ A single node functions exactly the same as cluster mode.
 It will consistently maintain the `Leader` status and never transition to `Candidate` or `Follower` states.
 
 
+### How do I store additional information about nodes in Openraft?
+
+By default, Openraft provide a [`BasicNode`] as the node type in a cluster.
+To store more information about each node in Openraft, define a custom struct
+with the desired fields and use it in place of `BasicNode`. Here's a brief
+guide:
+
+1. Define your custom node struct:
+
+```rust,ignore
+#[derive(...)]
+struct MyNode {
+    ipv4: String,
+    ipv6: String,
+    port: u16,
+    // Add additional fields as needed
+}
+```
+
+2. Register the custom node type with `declare_raft_types!` macro:
+
+```rust,ignore
+openraft::declare_raft_types!(
+   pub MyRaftConfig: 
+       // ... 
+       NodeId = u64,        // Use the appropriate type for NodeId
+       Node = MyNode,       // Replace BasicNode with your custom node type
+       // ... other associated types
+);
+```
+
+Use `MyRaftConfig` in your Raft setup to utilize the custom node structure.
+
+
 ### How to remove node-2 safely from a cluster `{1, 2, 3}`?
 
 Call `Raft::change_membership(btreeset!{1, 3})` to exclude node-2 from
@@ -188,6 +222,9 @@ pub(crate) fn following_handler(&mut self) -> FollowingHandler<C> {
 [`Linearizable Read`]: `crate::docs::protocol::read`
 [`leader_id`]:         `crate::docs::data::leader_id`
 
+[`BasicNode`]:        `crate::node::BasicNode`
+[`RaftTypeConfig`]:   `crate::RaftTypeConfig`
+
 [`RaftLogStorage::save_committed()`]: `crate::storage::RaftLogStorage::save_committed`
 
 [`RaftNetwork`]: `crate::network::RaftNetwork`