doc: Release notes and other docs for migration

Author: achow101

doc/managing-wallets.md

@@ -120,4 +120,29 @@ After that, `getwalletinfo` can be used to check if the wallet has been fully re
 $ bitcoin-cli -rpcwallet="restored-wallet" getwalletinfo
 ```
 
-The restored wallet can also be loaded in the GUI via `File` ->`Open wallet`.
+The restored wallet can also be loaded in the GUI via `File` ->`Open wallet`.
+
+## Migrating Legacy Wallets to Descriptor Wallets
+
+Legacy wallets (traditional non-descriptor wallets) can be migrated to become Descriptor wallets
+through the use of the `migratewallet` RPC. Migrated wallets will have all of their addresses and private keys added to
+a newly created Descriptor wallet that has the same name as the original wallet. Because Descriptor
+wallets do not support having private keys and watch-only scripts, there may be up to two
+additional wallets created after migration. In addition to a descriptor wallet of the same name,
+there may also be a wallet named `<name>_watchonly` and `<name>_solvables`. `<name>_watchonly`
+contains all of the watchonly scripts. `<name>_solvables` contains any scripts which the wallet
+knows but is not watching the corresponding P2(W)SH scripts.
+
+Migrated wallets will also generate new addresses differently. While the same BIP 32 seed will be
+used, the BIP 44, 49, 84, and 86 standard derivation paths will be used. After migrating, a new
+backup of the wallet(s) will need to be created.
+
+Given that there is an extremely large number of possible configurations for the scripts that
+Legacy wallets can know about, be watching for, and be able to sign for, `migratewallet` only
+makes a best effort attempt to capture all of these things into Descriptor wallets. There may be
+unforeseen configurations which result in some scripts being excluded. If a migration fails
+unexpectedly or otherwise misses any scripts, please create an issue on GitHub. A backup of the
+original wallet can be found in the wallet directory with the name `<name>-<timestamp>.legacy.bak`.
+
+The backup can be restored using the `restorewallet` command as discussed in the
+[Restoring the Wallet From a Backup](#16-restoring-the-wallet-from-a-backup) section

doc/release-notes-19602.md

@@ -0,0 +1,9 @@
+Wallet
+======
+
+Migrating Legacy Wallets to Descriptor Wallets
+---------------------------------------------
+
+An experimental RPC `migratewallet` has been added to migrate Legacy (non-descriptor) wallets to
+Descriptor wallets. More information about the migration process is available in the
+[documentation](https://github.com/bitcoin/bitcoin/blob/master/doc/managing-wallets.md#migrating-legacy-wallets-to-descriptor-wallets).