Update index.md (#1886)

Announce `rustdoc` output in Learn index See what's new section

doc/src/learn/index.md

@@ -14,11 +14,11 @@ For a deep dive into Sui technology, see the [Sui Smart Contracts Platform](../.
 
 Find the latest updates to these contents in this section:
 
+* [rustdoc](../build/install.md#source-code) - Find `rustdoc` output for `sui`, `narwhal` and `mysten-infra` projects at both Install and [Contribute to Sui](../contribute/index.md#download-sui).
 * [Sui DevNet](../explore/devnet.md) - Experiment with Sui DevNet: request gas tokens, mint/customize example NFTs, publish a Move module, and make a Move call.
 * [JSON-RPC API](../build/json-rpc.md) - Set up your own local Sui RPC Server and use the Sui JSON-RPC API to interact with a local Sui network.
 * [Narwhal and Tusk for consensus](../learn/architecture/consensus.md) - Learn about Narwhal and Tusk, Sui's high-throughput mempool and consensus engine.
 * [RPC API publishing](../build/json-rpc.md#sui_publish) - Follow instructions for publishing Move modules via the Publish endpoint.
-* [Wallet improvements](../build/wallet.md#active-address)- Employ an active (default) addresses and [use gas objects for transactions](../build/wallet.md#paying-for-transactions-with-gas-objects).
 
 See the Sui `doc/src` [history](https://github.com/MystenLabs/sui/commits/main/doc/src) for a complete changelog of updates to this site.