Some updates to Lighthouse book (#6995)

* #6447


  - Move some deprecated pages to a new section under `Archived`

- Remove fallback log in mev as the log will not be present after VC using `/eth/v3/validator/blocks` endpoint by default
- Add warning against using Btrfs file system (thank you @ChosunOne for the report)
- Add data shared by @mcdee  on tree states API queries time
- Rename partial withdrawals to validator sweep to differentiate it from the upcoming execution layer partial withdrawals
- Update NAT API response
- Update docs on IPv6

- Rename .md files to follow a standard prefix section name, e.g., installation_*.md, advanced_*.md
- Standardise .md files using underscore `_` instead of hyphen `-` to be consistent with other files naming conventions.

book/src/validator_manager.md

@@ -0,0 +1,35 @@
+# Validator Manager
+
+[Ethereum Staking Launchpad]: https://launchpad.ethereum.org/en/
+
+## Introduction
+
+The `lighthouse validator-manager` tool provides utilities for managing validators on a *running*
+Lighthouse Validator Client. The validator manager performs operations via the HTTP API of the
+validator client (VC). Due to limitations of the
+[keymanager-APIs](https://ethereum.github.io/keymanager-APIs/), only Lighthouse VCs are fully
+supported by this command.
+
+The validator manager tool is similar to the `lighthouse account-manager` tool,
+except the latter creates files that will be read by the VC next time it starts
+whilst the former makes instant changes to a live VC.
+
+The `account-manager` is ideal for importing keys created with the
+[staking-deposit-cli](https://github.com/ethereum/staking-deposit-cli). On the
+other hand, the `validator-manager` is ideal for moving existing validators
+between two VCs or for advanced users to create validators at scale with less
+downtime.
+
+The `validator-manager` boasts the following features:
+
+- One-line command to arbitrarily move validators between two VCs, maintaining the slashing protection database.
+- Generates deposit files compatible with the [Ethereum Staking Launchpad][].
+- Generally involves zero or very little downtime.
+- The "key cache" is preserved whenever a validator is added with the validator
+    manager, preventing long waits at start up when a new validator is added.
+
+## Guides
+
+- [Creating and importing validators using the `create` and `import` commands.](./validator_manager_create.md)
+- [Moving validators between two VCs using the `move` command.](./validator_manager_move.md)
+- [Managing validators such as delete, import and list validators.](./validator_manager_api.md)