add vscode extension link to the landing (#248)

Author: mkurnikov

src/content/docs/index.mdx

@@ -38,6 +38,7 @@ import ListCard from '~/components/ListCard.astro';
 
   <ListCard title="Tooling" iconName="terminal">
     - [Aptos CLI](/build/cli)
+    - [VSCode Extension](/build/smart-contracts/move-vscode-extension)
     - [Indexer API](/build/indexer/indexer-api)
     - [Official SDKs](/build/sdks)
     - [Testnet Faucet](/network/faucet)