docs(localization): add note for non-NDT users

[KYabuuchi]

Description

I added a note to users who use pose_estimator other than NDT.

Pre-review checklist for the PR author

The PR author must check the checkboxes below when creating the PR.

• I've confirmed the contribution guidelines.
• The PR follows the pull request guidelines.

In-review checklist for the PR reviewers

The Reviewers must check the checkboxes below before approval.

• The PR follows the pull request guidelines.

Post-review checklist for the PR author

The PR author must check the checkboxes below before merging.

• There are no open discussions or they are tracked via tickets.

After all checkboxes are checked, anyone who has write access can merge the PR.

[github-actions]

Documentation URL: https://autowarefoundation.github.io/autoware-documentation/pr-496/
Modified URLs:

• https://autowarefoundation.github.io/autoware-documentation/pr-496/how-to-guides/integrating-autoware/launch-autoware/localization/

[Motsu-san]