docs: Add quickstart guide for confidential tokens (#5786)

* docs: Add quickstart guide for confidential tokens

* Update docs/src/confidential-token/quickstart.md

Co-authored-by: samkim-crypto <[email protected]>

* Update docs/src/confidential-token/quickstart.md

Co-authored-by: samkim-crypto <[email protected]>

---------

Co-authored-by: samkim-crypto <[email protected]>

docs/src/confidential-token/quickstart.md

@@ -1,3 +1,103 @@
 ---
 title: Quick Start Guide
 ---
+
+The Token-2022 program provides confidential transfer functionality through the
+confidential transfer extension.
+
+This guide explains how to use the confidential transfer extension.
+
+Please see the [Token-2022 Introduction](../token-2022) for more general information
+about Token-2022 and the concept of extensions.
+
+## Setup
+
+See the [Token Setup Guide](../token#setup) to install the client utilities.
+Token-2022 shares the same CLI and NPM packages for maximal compatibility.
+
+### Example: Create a mint with confidential transfers
+
+To create a new mint with confidential transfers enabled, run:
+
+```console
+$ spl-token --program-id TokenzQdBNbLqP5VEhdkAS6EPFLC1PHnBqCXEpPxuEb create-token --enable-confidential-transfers auto
+```
+
+The `auto` keyword means that any token user can permissionlessly configure their
+account to perform confidential transfers.
+
+If you would like to gate confidential transfer functionality to certain users,
+you can set the approve policy to `manual`. With this approve policy, all users
+must be manually approved to perform confidential transfers. Anyone can still use
+the token non-confidentially.
+
+Note that you must configure your mint with confidential transfers at creation,
+and cannot add it later.
+
+### Example: Configure a token account for confidential transfers
+
+Account creation works as normal:
+
+```console
+$ spl-token create-account <MINT_PUBKEY>
+```
+
+Once the user creates their account, they may configure it for confidential transfers:
+
+```console
+$ spl-token configure-confidential-transfer-account --address <ACCOUNT_PUBKEY>
+```
+
+Note that only the account owner may configure confidential transfers for their
+account: only they should set the encryption key for their account. This is
+different from normal accounts, such as associated-token-accounts, where someone
+can create another person's account.
+
+### Example: Deposit confidential tokens
+
+Once the user configures their account for confidential transfers and has a
+non-confidential token balance, they must deposit their tokens from non-confidential
+to confidential:
+
+```console
+$ spl-token deposit-confidential-tokens <MINT_PUBKEY> <AMOUNT> --address <ACCOUNT_PUBKEY>
+```
+
+Note that the deposited tokens will no longer exist on the account's non-confidential
+balance: they have been completely moved into the confidential balance.
+
+### Example: Apply pending balance
+
+Whenever an account receives confidential tokens from transfers or deposits, the
+balance will appear in the "pending" balance, which means that the user cannot
+immediately access the funds.
+
+To move a balance from "pending" to "available", simply run:
+
+```console
+$ spl-token apply-pending-balance --address <ACCOUNT_PUBKEY>
+```
+
+### Example: Transfer confidential tokens
+
+Once an account has an available balance, a user may finally transfer the tokens
+to another account that has been configured for confidential transfers!
+
+```console
+$ spl-token transfer <MINT_PUBKEY> <AMOUNT> <DESTINATION_PUBKEY> --confidential
+```
+
+This operation takes a little bit longer since it requires multiple dependent
+transactions, but it's still only a few seconds.
+
+### Example: Withdraw confidential tokens
+
+A user whose account has an available confidential balance may withdraw those
+tokens back into their non-confidential balance.
+
+```console
+$ spl-token withdraw-confidential-tokens <MINT_PUBKEY> <AMOUNT> --address <ACCOUNT_PUBKEY>
+```
+
+Be sure to apply any pending balance before running this command to be sure that
+all tokens are available.