v1.15: Cancel dumpless update (#3257)

* add task `type`s

* add rollback instructions

* first draft ready

Author: guimachiavelli

learn/update_and_migration/updating.mdx

@@ -47,9 +47,9 @@ Once the project has been successfully updated, you will receive an email confir
 
 ## Updating a self-hosted Meilisearch instance
 
-<Warning>
 You may update a self-hosted instance in one of two ways: with or without a dump.
 
+<Warning>
 This guide only works for v0.15 and above. If you are using an older Meilisearch release, please [contact support](https://discord.meilisearch.com) for more information.
 </Warning>
 
@@ -156,9 +156,21 @@ Meilisearch should launch normally and immediately create a new `UpgradeDatabase
 
 While the task is processing, you may continue making search queries. You may also enqueue new tasks. Meilisearch will only process new tasks once `UpgradeDatabase` is completed.
 
-<Warning>
-If after the upgrade is completed the task status is set to `failed` or Meilisearch returns internal error messages to your queries, [restart your instance from the snapshot](/learn/data_backup/snapshots#starting-from-a-snapshot) you generated during step 1. You may then retry the upgrade, or upgrade using a dump. You are also welcome to open an issue on the [Meilisearch repository](https://github.com/meilisearch/meilisearch).
-</Warning>
+#### Rolling back an update
+
+If the upgrade is taking too long, or if after the upgrade is completed its task status is set to `failed`, you can cancel the upgrade task.
+
+Cancelling the update task automatically rolls back your database to its state before the upgrade began.
+
+After launching Meilisearch with `--experimental-dumpless-upgrade` flag:
+
+1. Cancel the `databaseUpgrade` task
+2. If you cancelled the update before it failed, skip to the next step. If the update failed, relaunch Meilisearch using the binary of the version you were upgrading to
+3. Wait for Meilisearch to process your cancellation request
+4. Replace the new binary with the binary of the previous version
+5. Relaunch Meilisearch
+
+If you are upgrading Meilisearch to \<= v1.14, you must instead [restart your instance from the snapshot](/learn/data_backup/snapshots#starting-from-a-snapshot) you generated during step 1. You may then retry the upgrade, or upgrade using a dump. You are also welcome to open an issue on the [Meilisearch repository](https://github.com/meilisearch/meilisearch).
 
 ### Using a dump
 

reference/api/tasks.mdx

@@ -74,7 +74,7 @@ This value is always `null` for [global tasks](/learn/async/asynchronous_operati
 ### `type`
 
 **Type**: String<br />
-**Description**: Type of operation performed by the task. Possible values are `indexCreation`, `indexUpdate`, `indexDeletion`, `indexSwap`, `documentAdditionOrUpdate`, `documentDeletion`, `settingsUpdate`, `dumpCreation`, `taskCancelation`, `taskDeletion`, and `snapshotCreation`
+**Description**: Type of operation performed by the task. Possible values are `indexCreation`, `indexUpdate`, `indexDeletion`, `indexSwap`, `documentAdditionOrUpdate`, `documentDeletion`, `settingsUpdate`, `dumpCreation`, `taskCancelation`, `taskDeletion`, `databaseUpgrade`, `documentEdition`, and `snapshotCreation`
 
 ### `canceledBy`