token-2022: Add intro docs, structure for more docs (#3384)

* token-2022: Add intro docs, structure for more docs

* Address feedback

* Remove the word "migration"

Author: joncinque

docs/sidebars.js

@@ -2,6 +2,17 @@ module.exports = {
   docs: [
     "introduction",
     "token",
+    {
+      type: 'category',
+      label: 'Token-2022',
+      collapsed: true,
+      items: [
+        "token-2022",
+        "token-2022/extensions",
+        "token-2022/wallet-migration",
+        "token-2022/onchain-migration",
+      ],
+    },
     "token-swap",
     "token-lending",
     "associated-token-account",

docs/src/token-2022.md

@@ -0,0 +1,129 @@
+---
+title: Token-2022 Program
+---
+
+A token program on the Solana blockchain, defining a common implementation for
+fungible and non-fungible tokens.
+
+The Token-2022 Program is a superset of the functionality provided by the
+[Token Program](token.mdx), deployed to all networks.
+
+| Information | Account Address |
+| --- | --- |
+| Token-2022 Program | `TokenzQdBNbLqP5VEhdkAS6EPFLC1PHnBqCXEpPxuEb` |
+
+## Motivation
+
+The existing Token Program serves most needs for fungible and non-fungible tokens
+on Solana through a simple set of interfaces and structures. It has been rigorously
+audited since its initial deployment in 2020.
+
+As more developers have come to Solana with new ideas, however, they have forked the
+Token Program to add functionality. It's simple to change and deploy the program,
+but it's difficult to achieve adoption across the ecosystem.
+
+Solana's programming model requires programs to be included in transactions
+along with accounts, making it complicated to craft transactions involving
+multiple token programs.
+
+On top of the technical difficulty, wallets and on-chain programs must trust any
+token program that they choose to support.
+
+We need to add new token functionality, with minimal disruption to users, wallets,
+and dApps. Most importantly, we must preserve the safety of existing tokens.
+
+A new token program, Token-2022, was developed to achieve both of these goals,
+deployed to a different address than the Token program.
+
+## Concept
+
+To make adoption as easy as possible, the functionality and structures in
+Token-2022 are a strict superset of Token.
+
+### Instructions
+
+Token-2022 supports the exact same instruction layouts as Token, byte for
+byte. For example, if you want to transfer 100 tokens on a mint with 2 decimals,
+you create a `TransferChecked` instruction, with this byte-representated data:
+
+```
+[12, 100, 0, 0, 0, 0, 0, 0, 0, 2]
+ ^^ TransferChecked enum
+     ^^^^^^^^^^^^^^^^^^^^^^^^ 100, as a little-endian 64-bit unsigned integer
+                               ^ 2, as a byte
+```
+
+This format means the exact same thing to both Token and Token-2022. If you want
+to target one program over another, you just need to change the `program_id` in
+the instruction.
+
+All new instructions in Token-2022 start where Token stops. Token has 25 unique
+instructions, with indices 0 through 24. Token-2022 supports all of these
+instructions, and then adds new functionality at index 25.
+
+There are no plans to ever add new instructions to Token.
+
+### Mints and Accounts
+
+For structure layouts, the same idea mostly applies. An `Account` has the same
+exact representation between Token and Token-2022 for the first `165` bytes, and
+a `Mint` has the same representation for the first `82` bytes.
+
+### Extensions
+
+New functionality requires new fields in mints and accounts, which
+makes it impossible to have the exact same layout for all accounts in Token-2022.
+
+New fields are added in the form of extensions.
+
+Mint creators and account owners can opt-in to Token-2022 features. Extension data
+is written after the end of the `Account` in Token, which is the byte at index
+`165`.  This means it is always possible to differentiate mints and accounts.
+
+You can read more about how this is done at the
+[source code](https://github.com/solana-labs/solana-program-library/tree/master/token/program-2022/src/extensions/mod.rs).
+
+Mint extensions currently include:
+
+* confidential transfers
+* transfer fees
+* closing mint
+* interest-bearing tokens
+
+Account extensions currently include:
+
+* memo required on incoming transfers
+* immutable ownership
+
+Extensions can be mixed and matched, which means it's possible to create a mint
+with only transfer fees, only interest-bearing tokens, both, or neither!
+
+### Associated Token Accounts
+
+To make things simpler, there is still only one associated token account
+program, that creates new token accounts for either Token or Token-2022.
+
+## Getting Started
+
+To get started with Token-2022:
+
+- [Install the Solana Tools](https://docs.solana.com/cli/install-solana-cli-tools)
+- [Extension Guide](token-2022/extensions.md)
+- [Wallet Guide](token-2022/wallet.md)
+- [On-Chain Program Guide](token-2022/onchain.md)
+
+For existing functionality in the Token Program, see the [token docs](token.mdx).
+The Token functionality will always apply to Token-2022.
+
+## Source
+
+The Token-2022 Program's source is available on
+[GitHub](https://github.com/solana-labs/solana-program-library/tree/master/token/program-2022).
+
+For information about the types and instructions, the Rust docs are available at
+[docs.rs](https://docs.rs/spl-token-2022/latest/spl_token_2022/).
+
+## Security Audits
+
+The Token-2022 Program is currently under multiple audits to ensure safety of
+funds. All audits will be published here as they are completed.

docs/src/token-2022/extensions.md

@@ -0,0 +1,5 @@
+---
+title: Extension Guide
+---
+
+Coming soon!

docs/src/token-2022/onchain.md

@@ -0,0 +1,5 @@
+---
+title: On-chain Program Guide
+---
+
+Coming soon!

docs/src/token-2022/wallet.md

@@ -0,0 +1,5 @@
+---
+title: Wallet Guide
+---
+
+Coming soon!