Transfer account guide (#267)

* Guide to migrating a pwned account to a new wallet

* Moar docs

TRANSFER_ACCOUNT_GUIDE.md

@@ -0,0 +1,55 @@
+## TRANSFER ACCOUNT GUIDE
+
+A user got their wallet pwned and you need to move them to a new mrgn account? Read on.
+
+Before you begin:
+
+- You must be an admin of the group where the user account is based. If this is a mrgn-owned group,
+  that's probably the multisig (AZtUUe9GvTFq9kfseu9jxTioSgdSfjgmZfGQBmhVpTj1). If this is arena,
+  that's the pool owner/creator.
+- If you have admin, consider freezing the account with `SetAccountFlag` (passing `DISABLED_FLAG`)
+  to prevent the attacker from doing anything.
+
+You will need:
+
+- Contact with the affected user (they must sign to conclude the process)
+- Access to the mrgn CLI (clients/rust/marginfi-cli)
+- Rust 1.75.0 (as of December 2024)
+- Access to either the front end (at /migrate/account) or a TS scripting environment where you can run a simple TS script. If using the latter, we'll assume the affected wallet is located at `/keys/affected_wallet.json`
+- (Optional) A wallet with sol at a location you know. We'll assume it's at
+  `/keys/some_wallet.json`. You'll need this for most CLI interactions but not in this particular
+  use case.
+
+Steps:
+
+- Open terminal at `clients/rust/marginfi-cli`
+- Create a profile:
+
+```
+cargo run profile create \
+--name mainnet-group-ms \
+--cluster mainnet \
+--rpc-url https://api.mainnet-beta.solana.com \
+--group 4qp6Fx6tnZkY5Wropq9wUYgtFxXKwE6viZxFHg3rdAG8 \
+--program-id MFv2hWf31Z9kbCa1snEPYctwafyhdvnV7FZnsebVacA \
+--multisig AZtUUe9GvTFq9kfseu9jxTioSgdSfjgmZfGQBmhVpTj1 \
+--keypair-path ~/keys/some_wallet.json \
+--fee-payer ~/keys/some_wallet.json
+```
+
+Feel free to use a custom rpc instead if you have one. Omit the last two lines if you don't have a local wallet with SOL.
+
+- `cargo run profile set mainnet-group-ms` to use this profile, `cargo run profile show` to confirm your settings.
+- Run this ix to generate a tx to set the migration flag:
+```
+cargo run account set-flag THE_COMPROMISED_ACCOUNT \
+  --account-migration-enabled
+```
+* confirm the profile name when prompted to proceed
+* Copy the tx contents (everything between the --------) from the CLI output. Open Squads and go to
+  Developers > TX Builder> Import base28 encoded tx. Paste what you copied.
+* Type a description for the tx and hit Initiate Transaction. Wait for votes and execute.
+
+Steps for User:
+* After admin completes the above, navigate to the migration page (or script) to sign the finalized
+  migration ix.