dhi: update mirroring ux (#23571)

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## Description

Updated mirroring flow.
- Removed the step to choose a name. Users can no longer choose a name
unless it's already been mirrored. Even then, there's now a default
name, so not required.
- Removed the screenshot of the mirror screen. The screen is now
different. Removed instead of updated as there is nothing complex.
Previously had it to show an example of the name prefixed with `dhi-`.
 - Updated screenshot of mirror button.

Updated topics:
-
https://deploy-preview-23571--docsdocker.netlify.app/dhi/get-started/#step-3-mirror-the-image
-
https://deploy-preview-23571--docsdocker.netlify.app/dhi/how-to/mirror/#mirror-an-image-repository

## Related issues or tickets

https://docker.slack.com/archives/C0989V6TAK0/p1760358028944909

## Reviews

<!-- Notes for reviewers here -->
<!-- List applicable reviews (optionally @tag reviewers) -->

- [ ] Editorial review

---------

Signed-off-by: Craig Osterhout <[email protected]>

Author: craig-osterhout

content/manuals/dhi/get-started.md

@@ -75,13 +75,7 @@ it.
    > **View in repository** to see the mirrored image's location or mirror it to
    > another repository.
   
-2. Follow the on-screen instructions to choose a name. For this guide, the
-   example uses the name `dhi-python`. Note that the name must start with
-   `dhi-`.
-
-   ![Mirror a repository page](./images/dhi-mirror-screen.png)
-
-3. Select **Create repository** to start the mirroring process.
+2. Follow the on-screen instructions to mirror the repository.
 
 It may take a few minutes for all the tags to finish mirroring. Once
 mirrored, the image repository appears in your organization's namespace. For

content/manuals/dhi/how-to/mirror.md

@@ -47,7 +47,7 @@ you can:
    repository
 
 After mirroring a repository, the repository appears in your organization's
-repository list under the name you specified, prefixed by `dhi-`. It will
+repository list, prefixed by `dhi-`. It will
 continue to receive updated images.
 
 ![Repository list with mirrored repository showing](../images/dhi-python-mirror.png)