docs: rebase changesets (#1050)

Updating the docs for the new changeset rebase functionality

@MaedahBatool: Would you take this PR and merge it into the 6.2 branch

Author: bahrmichael

docs/batch-changes/rebasing-changesets.mdx

@@ -0,0 +1,36 @@
+# Rebasing changesets
+
+<p className="subtitle">Learn how to rebase your existing changesets.</p>
+
+<Callout type="note">This feature is supported for Sourcegraph versions 6.2 or more.</Callout>
+
+If your codehost requires changesets to be up to date with the main branch, you can use the rebase functionality of the Web UI to update the changesets.
+
+<Callout type="warning">Rebasing does not resolve merge conflicts.</Callout>
+
+## Requirements
+
+- Sourcegraph instance with repositories in it. See the [Quickstart](/#quick-install) guide on how to set up a Sourcegraph instance
+- A [global service account token](/batch-changes/configuring-credentials#global-service-account-tokens) for Batch Changes (**a personal access token cannot currently be used for importing changesets**)
+
+## Select changesets to rebase
+
+After navigating to the changesets of your batch change, select one or more **published** changesets to rebase. You can only rebase changesets after they have been published to the codehost.
+
+![List of changesets with two of them selected](https://storage.googleapis.com/sourcegraph-assets/docs/images/batch_changes/2025/rebase_changesets.png)
+
+If a changeset is already up to date with the main branch, rebasing will result in no changes.
+
+## Start the rebase bulk operation
+
+With all applicable changesets selected, click the **Select action** button, and then select **Rebase changesets**.
+
+![List of changesets and dropdown overlay](https://storage.googleapis.com/sourcegraph-assets/docs/images/batch_changes/2025/rebase_dropdown.png)
+
+Confirm the popup to start the rebase bulk operation.
+
+![Popup to confirm rebase action](https://storage.googleapis.com/sourcegraph-assets/docs/images/batch_changes/2025/rebase_confirm.png)
+
+You can see the progress of the rebase operation in the **Bulk Actions** tab.
+
+![List of bulk operations showing that rebase has completed](https://storage.googleapis.com/sourcegraph-assets/docs/images/batch_changes/2025/rebase_status.png)

src/data/navigation.ts

@@ -151,6 +151,7 @@ export const navigation: NavigationItem[] = [
 						subsections: [
 							{ title: "Publishing Changesets", href: "/batch-changes/publishing-changesets", },
 							{ title: "Tracking Changesets", href: "/batch-changes/tracking-existing-changesets", },
+							{ title: "Rebasing Changesets", href: "/batch-changes/rebasing-changesets", },
 						]
 					},
 					{